Roberto León / NBC News

Josefina Vidal, Cuba's director of U.S. Affairs at the Ministry of Foreign Affairs, addresses the media in Havana on Wednesday.

HAVANA -- A Cuban official on Wednesday accused the U.S. government of “lying” about the health of Alan Gross, an American contractor serving a 15-year prison sentence here, in an effort to force his release. 

Denying speculation that the 63-year-old Gross has cancer or is otherwise in poor health, Foreign Ministry official Josefina Vidal said at a press conference in the Cuban capital that the 63-year-old American has "been treated decently and well in prison.”

She also stated that “his health has "not deteriorated" and that he "speaks regularly with friends and family."

"Gross has been seen by the most qualified Cuban medical specialists," Vidal said. "The U.S. government is lying to suggest that he has cancer and that he is not receiving adequate treatment." If these lies continue, she said, "Cuba will present new evidence that shows Gross is not sick."

Vidal’s statement came in response to increasing pressure from the U.S. government and lawmakers to release Gross, who was convicted in 2009 of "acts against the independence and/or territorial integrity of the state” for  distributing telecommunications equipment to Cuba’s tiny Jewish community.

At the time, Gross was in Cuba on a  tourist visa, working  for Development Alternatives, Inc., a State Department contractor, as an "independent business and economic development consultant" under an $8.6 million contract from the U.S. Agency for International Development.

The court that convicted him described the effort as an effort to subvert the Cuban government.

“It was demonstrated that (Gross) illegally introduced telecommunications equipment in Cuba to create internal networks as part of a program of the government of the United States that aimed to promote destabilizing actions in the country and subvert Cuban constitutional order," it said at the time.

Since his imprisonment more than three years ago, Gross has lost more than 100 pounds and developed a mass on his right shoulder blade, which Cuban doctors diagnosed as a non-malignant hematoma that would be reabsorbed within a few months, according to Reuters.

Related stories

Cuba pushes swap: its spies jailed in US for American contractor held in Havana

American jailed in Cuba wants US to sign non-belligerency pact to speed release

Gross’ wife, Judy, has been leading a public relations campaign in the United States for her husband’s release on humanitarian grounds. An American radiologist she consulted said last month that the mass had not been properly evaluated and speculated that it could be cancerous. The radiologist, Alan Cohen, said that Gross needed an urgent evaluation – and likely a biopsy of the mass – preferably at a facility in the United States.

At a press conference on Capitol Hill Tuesday – the fourth anniversary of her husband’s imprisonment – Judy Gross said her husband “is frail, suffers from chronic pain ... and still doesn’t know whether he has cancer.”

U.S. State Department spokesman Mark Toner sounded a similar theme on Monday.

“Mr. Gross has lost more than 100 pounds and suffers from severe degenerative arthritis that affects his mobility, and other health problems,” he said in a statement. “His family is anxious to evaluate whether he is receiving appropriate medical treatment, something that can best be determined by having a doctor of his own choosing examine him.”

While resisting calls to release Gross, Cuban officials have floated an alternative to resolve the impasse: They say they will free Gross if President Barack Obama agrees to release five Cuban spies held in the U.S.

The spies – known as the Cuban Five – are national heroes in Cuba as a result of their mission in the late 1990s to infiltrate  anti-Castro exile groups in South Florida that Havana suspected of plotting terrorist attacks inside Cuba. They were convicted in Miami in June 2001 of conspiracy to commit espionage, conspiracy to commit murder, acting as an agent of a foreign government, and other illegal activities.

Vidal referred to this scenario on Tuesday, reiterating “Cuba's willingness to immediately start talks with the U.S. government to find a humanitarian solution that is mutually beneficial to both parties." She also stated that her government would not make a "unilateral" move and release Gross because the "problem also belongs to the U.S." -- referring to the Cuban Five.

Gross himself pushed for a diplomatic solution in a meeting on Nov. 28 with Peter Kornbluh, a Cuba specialist from the National Security Archives in Washington.

"He’s angry, he’s frustrated, he’s dejected — and he wants his own government to step up" and negotiate, Kornbluh told NBC News last week. "His message is that the United States and Cuba have to sit down and have a dialogue without preconditions. … He told me that the first meeting should result in a non-belligerency pact being signed between the United States and Cuba."

Mary Murray is an NBC News producer; NBC National Investigative Correspondent Michael Isikoff also contributed to this report.

More from Open Channel:

Follow Open Channel from NBCNews.com on Twitter and Facebook

HAVANA, Cuba — Three years after he was arrested in Havana, jailed American contractor Alan Gross is asking the U.S. government to sign a "non-belligerency pact" with Cuba as a first step toward negotiating his release, according to a Cuba policy analyst who just visited him.

Peter Kornbluh , right, stands with Alan Gross, in a picture taken on Kornbluh's iPhone by a guard during his visit to the Havana prison where Gross is being held.

Peter Kornbluh, a Cuba specialist at the National Security Archives, a nonprofit research center in Washington, met with Gross for four hours on Wednesday at the military hospital in Havana where the contractor is being held. He said Gross appeared "extremely thin" — he has lost over 100 pounds since his arrest —and dispirited.

"He’s angry, he’s frustrated, he’s dejected — and he wants his own government to step up" and negotiate, said Kornbluh. "His message is that the United States and Cuba have to sit down and have a dialogue without preconditions. … He told me that the first meeting should result in a non-belligerency pact being signed between the United States and Cuba."

Gross' comments appear to represent a new tack in an aggressive public relations campaign to win his freedom. His supporters have planned a candlelight vigil outside the Cuban interests section in Washington D.C., on Sunday and the U.S. Senate is poised to take up a resolution Monday demanding his release, Gross’ wife, Judy, has also become increasingly critical of the U.S. government for not doing more to demand that her 63-year-old husband be allowed to return home.

Jose Luis Magana / AP

Judy Gross at her home in Washington, D.C. on Nov. 29.

"He feels like a soldier in the field left to die," she said at a press conference in Washington last week.

Gross, who worked for an Agency for International Development contractor, was arrested by the Cubans on Dec. 3, 2009, and accused of smuggling sophisticated satellite and other telecommunications equipment into  the country to give to the island’s tiny Jewish community. Gross has said he was only trying to increase Internet access  in Cuba. But he was convicted by a Cuban court in March of last year for crimes "against the independence and territorial integrity of the state" and sentenced to 15 years.

Related coverage

Cuba pushes swap: its spies jailed in US for American contractor held in Havana

Slideshow: Castro through the years

Last month, Gross and his wife filed a $60 million lawsuit against the U.S. government and the contractor he was working for, Development Alternatives, charging he was used as a "pawn" in a U.S. government program to change the Castro regime and never advised about the dangers he faced bringing high tech satellite transmission equipment into Cuba. (The State Department, of which AID is a part and which has repeatedly called for Gross’ release, declined comment. Development Alternatives has released a statement saying it has "no higher priority" than bringing Gross home.) 

Kornbluh, who has advocated closer U.S.-Cuba dialogue, was in Havana last week to attend a conference marking the 50th anniversary of the Cuban missile crisis. He was granted permission to visit Gross by Cuban officials. (The Cubans so far have denied all news media requests to meet with him.) He said Gross was most upset about being unable to return home to see members of his family who are ill, especially his 90-year-old mother in Texas who has cancer.

Slideshow: US and Cuba: A long tense relationship

Keystone / Getty Images

Ever since U.S.-backed Cuban President Fulgencio Batista was forced from power by rebels led by Fidel Castro in 1958, the relationship between the two nations has been fraught with difficulties.

Launch slideshow

"He really wants to see his mother, who is quite old and infirm,” said Kornbluh. When Kornbluh had his photo taken with Gross, the contractor held up a photo that read: “Hi Mom.” When he asked Gross what he wanted to get out of the lawsuit, the contractor replied: “I want to see my wife and I want to see my mother."

To accomplish that, Gross is seeking to nudge the Obama administration, according to Kornbluh. Gross knows that his freedom "is going to depend on his government negotiating in good faith with the Cubans," said Kornbluh. "His message to Barack Obama is: I’m fired up and ready to go. Where are you at this moment?"

Michael Isikoff is NBC News' national investigative correspondent; NBC News producer Mary Murray also contributed to this report.

More from Open Channel:

• Cuba pushes swap: its spies jailed in US for  American jailed in Havana
• Livestock falling ill in fracking regions
• Tobacco industry used trade pacts to try to snuff out anti-smoking laws
• Jeb Bush's reputation as education reformer gets a second look
• As fighting raged in Syria, Russia sent tons of cash to Damascus, records show
• One email exposes millions to ID theft risk in South Carolina cyberattack
• Study finds breast cancer risk for women in auto plastics factories
• Jill Kelley email: Petraeus, Allen sought help hushing 'Bubba the Love Sponge'

Follow Open Channel from NBCNews.com on Twitter and Facebook

Peter Kahn / AP

American Alan Gross in 2009, left, and in 2012, right. A U.S. doctor said that Gross' weight loss, and a review of CT and ultrasound scans suggest Gross should be rigorously evaluated for cancer. He has a mass behind his right shoulder blade that Cuban doctors have diagnosed as a hematoma.

Alan Gross, a 63-year-old U.S. citizen imprisoned in Cuba for nearly three years, may be suffering from untreated cancer, according to a U.S. doctor who has reviewed Gross’ medical records — a conclusion that is at odds with the government in Havana, which has maintained that the American is in normal health.

Gross, a contractor for the United States government, was arrested as for subversion of the state in late 2009, and his case is a sticking point in U.S.-Cuban relations. The latest questions about his health have pushed his case to the forefront again.

Five months ago, Gross developed a mass behind his right shoulder blade, which doctors in Cuba diagnosed as a hematoma that would be reabsorbed within a few months, according to Reuters.

But an American radiologist consulted by Gross' wife to review his CT and ultrasound scans said the mass had not been properly evaluated, according to a doctor's statement released by Gross’ attorney Jared Genser.

Maryland-based radiologist Alan Cohen said the scans, combined with news that Gross has lost 105 pounds since his December 2009 arrest — suggest to him that Gross needs urgent evaluation — and very likely a biopsy of the mass — preferably at a facility in the United States.

A "soft tissue mass in an adult who has lost considerable weight must be assumed to represent a malignant tumor unless proven to be benign," said Cohen in a letter obtained by NBC News.

"If the mass is a soft tissue sarcoma and treated aggressively there is a good chance of cure; if on the other hand it is not treated aggressively and early and it spreads to lung and liver, his life expectancy would be about three months. Several months have already been wasted and the clock is ticking," Cohen wrote in the letter.

Attorney Genser said he hopes the doctor's evaluation, will raise the stakes enough for Cuba to take action.

"It is critically important that Alan Gross get competent medical care as quickly as possible," he said. "We hope this independent medical review demonstrates the need for that to happen immediately. I would urge the government of Cuba to allow Alan to be receive a doctor of his choosing to do a medical examination to evaluate his tumor."

Gross was arrested for "crimes against the state" and sentenced to 15 years for providing satellite equipment and service to Cuban Jewish groups.

At the time of his arrest, the Baltimore native was working for Development Alternatives, a subcontractor for the U.S. Agency for International Development to set up an intranet system, which his attorneys say was for sharing information such as recipes and prayers among the Jewish community in Cuba.

USAID’s Cuba program focuses its efforts on "increasing the ability of Cubans to participate in civic affairs and improve human rights conditions on the island," according to the federal agency's website. It had funding of $20 million for fiscal 2012.

Gross' arrest put an end to a brief period of warming in U.S.-Cuban relations, which had been chilly since the 1959 revolution led by Fidel Castro that established a communist state.

So far, there's no sign that either the U.S. or Cuba has budged on the issue.

Josefina Vidal, head of the North American Division at Cuba's Foreign Ministry, told NBC News that her government has offered to "have a dialogue with the US government to solve all our problems and that would include trying to find a humanitarian solution to Mr. Gross on a reciprocal basis. The U.S. government is responsible for the situation Mr. Gross finds himself in."

Vidal said there is no active negotiation currently underway between the two governments with the aim to free Gross. She asserted that "while we have conveyed our willingness to sit down and talk, to initiate a negotiation, we are still waiting for a response to our offer."

She did not specify what was entailed in that offer. Cuba has suggested in the past that Gross could be released in exchange release by the United States of four Cubans nationals held on espionage and murder conspiracy charges.

The idea been firmly rejected by the U.S. government, most recently by State Department spokeswoman Victoria Nuland in March, who said that Gross should be released unconditionally. The cases are not comparable, Nuland said, because "Gross is not a spy."

On Sept. 25, a bipartisan group of U.S. senators sent a letter to Cuban President Raul Castro calling for Gross’ release, calling his detention "a major obstacle" to improving relations.  The letter, signed by 44 senators was U.S. legislators’ most strident effort on Gross’s behalf to date.

Judy Gross, has repeatedly appealed to government officials on both sides to negotiate her husband's release. On Tuesday, in a letter released by Genser, she appealed to Cuban President Raul Castro to allow her husband to be examined by a doctor chosen by the family.

"President Castro, I beg you not to let my husband die on your watch," Judy Gross said. "Your country claims to have such a wonderful health care system — yet why have your doctors misdiagnosed him and failed to order the right tests to determine what is actually happening?"

This article includes reporting by Reuters and The Associated Press.

Follow Kari Huus on Facebook

More content from NBCNews.com:

• A week later, search still on for 73-year-old accused of killing daughter-in-law
• Video: Like hurricanes, winter storms to get names too
• Cell phone video shows cop striking woman after Philadelphia parade
• State Dept: Missing American journalist Austin Tice believed held by Syria regime
• NYPD commissioner blames rise in crime rate on Apple thefts

Follow US News from NBCNews.com on Twitter and Facebook

Geovani Fernandez / AP

In this photo released by Cuba's state-run Granma newspaper, Cuba's President Raul Castro, right, speaks with U.S. Sen. Patrick Leahy, left, a Democrat from Vermont, as U.S. Senator Richard Shelby, a Republican from Alabama, behind right, watches in Havana, Cuba, on Feb. 24, 2012.

Updated 1:38 p.m. ET: HAVANA, Cuba -- A senior U.S. senator met with imprisoned American Alan Gross and discussed the man's case in a long sit-down with Cuban President Raul Castro, but said Friday that he doesn't expect Gross to be released any time soon.

Sen. Patrick Leahy, a Democrat from Vermont, said he saw Gross on Thursday afternoon at a Havana military prison. He and Sen. Richard Shelby, a Republican from Alabama, later met for 2 1/2 hours with Castro and offered to take Gross back to the United States on their plane.

"You can imagine how far that went," Leahy said in a phone interview Friday with The Associated Press. He added that "we have a long way to go" to win Gross's release.

The 62-year-old Maryland native is serving a 15-year jail term for spiriting satellite and other communications equipment onto the island while on a USAID-funded democracy-building program. Cuba considers the programs an attempt to destabilize the government, and Gross was convicted of crimes against the state, not espionage.

The Gross affair has chilled relations between the U.S. and Cuba and short-circuited any chance of rapprochement since President Barack Obama took office.

The Gross family wants Castro to pardon him on humanitarian grounds because his mother and adult daughter both have cancer, a call backed by the Obama administration, which insists Gross is innocent.

Leahy said Castro agreed that Gross "was no spy." Gross spoke virtually no Spanish and traveled to Cuba five times under his own name before his arrest in December 2009.

The talks with Castro and the senators was the first high-level meeting between the Cold War enemies since former President Jimmy Carter dined with Castro during a visit to the island in April 2010. Leahy said the late-night meeting was cordial and open.

The meeting took place as the Cuban diplomatic mission in Washington announced plans to host what it called the "1st National Encounter" with Cubans living in the United States. The meeting will bring together Cuban-Americans "who have respectful links to their country," in order to discuss "the normalization of relations" between Cuba and the exile community in the United States, the statement said.

Leahy said Castro brought up the case of five Cuban agents sentenced to long jail terms in the United States, including one who was released last year but has not been allowed to return to Cuba while he serves out three years probation.

Leahy said Castro never explicitly linked Gross' fate with that of the agents, who were jailed in 1998, but "he made it very clear that while we may be concerned for Mr. Gross and have humanitarian reasons to be, they are very concerned about the five (agents) and have humanitarian and family reasons too."

While the agents' case is largely forgotten in the United States, it remains a cause celebre in Cuba, where the government hails the "Cuban Five" as heroes who were only trying to detect and prevent violent attacks against their country by exile groups.

Cuban officials have stopped short of linking the cases, but have said no one should expect the island to free the 62-year-old American in a "unilateral gesture."

Gross's legal appeals have been exhausted, but his family has asked Castro to consider a pardon on humanitarian grounds. Gross, who was portly when arrested in December 2009, has lost about 100 pounds and is now rail thin. His elderly mother and adult daughter are both battling cancer.

Leahy said Gross appeared in reasonably good spirits during the visit, but that he also indicated his two years of detention had taken a toll on his health.

"He obviously wants to leave. He feels that his health has been endangered," Leahy said, adding that he snapped several pictures of Gross to bring back to his wife, Judy.

Cuban state-run media carried images of the meeting between Castro and the senators, though they gave no details of what was discussed. Cuban media said Cuban Foreign Minister Bruno Rodriguez was also present.

The senators are part of an American congressional delegation touring Cuba, Haiti and Colombia. The other members of the delegation, all Democrats, were Sens. Christopher Coons of Delaware and Kent Conrad of North Dakota and Reps. Peter Welch of Vermont and Xavier Becerra of California.

The Associated Press and Reuters contributed to this report.

More from msnbc.com and NBC News:

• Australia's 'dingo baby' mystery finally solved?
• Beijing's pollution could cut 5 years off lifespan, expert says
• Clinton: Syria rebels will get arms 'somehow'
• NBC's Kabul correspondent discusses Quran outrage