Anjum Naveed / AP
Pakistan's President Asif Ali Zardari listens to a reporter at a press conference in Rawalpindi, Pakistan, in this picture taken on Aug. 15, 2010.
Updated at 6:06 a.m. ET
ISLAMABAD -- Pakistani President Asif Ali Zardari has traveled to Dubai after falling ill, fuelling rumors Wednesday of his possible resignation.
Close associates of the president told the Associated Press he is currently "unwell," but did not provide specifics. His condition did not appear to be life-threatening, they said, speaking on condition of anonymity because of the sensitivity of the issue.
Zardari's office said he was undergoing routine medical tests and a check-up "as planned."
However, Reuters cited a source in Dubai as saying that Zardari had suffered a minor heart attack.
"Two days ago, he had chest pain," the source added.
Prime Minister Yusuf Raza Gilani's office released a statement saying Zardari "went to Dubai following symptoms related to his pre-existing heart condition."
The president's spokesman denied a media report that the trip meant Zardari, who has been under pressure from a memo scandal that forced the Pakistani ambassador to the U.S. to resign, would cite failing health as a pretext to step down.
"All these reports are untrue, imaginary and speculative," spokesman Farhatullah Babar told The Associated Press.
'Noose was getting tighter'
An article published Tuesday on the website of Foreign Policy magazine quoted an unnamed former U.S. government official as saying Zardari was "incoherent" when he spoke with President Barack Obama by telephone over the weekend.
Parts of the U.S. government were also informed that Zardari had a "minor heart attack" on Monday night and might resign on account of "ill health" amid the uproar over the memo scandal, the source said.
"The noose was getting tighter -- it was only a matter of time," the former official reportedly told Foreign Policy.
The story quickly spread on Twitter and it was picked up by Pakistan's ratings-hungry television channels.
Rumors also circulated on Twitter of an army takeover on Tuesday night, but that was quickly recanted by the original poster.
"Some elements blew up this to create unrest in the country," said Fauzia Wahab, a senior member of Zardari's Pakistan People's Party. "His visit to Dubai and having a medical check-up is perfectly normal."
Foreign Policy also quoted a source close to Zardari as saying that "rumors of a silent coup are sometimes a way of trying to effect a silent coup. It won't happen."
Zardari, a canny political operator, has survived many predictions of his downfall since he became president in 2008.
A Dubai-based member of Zardari's party, Mian Muneer Hans, said the president landed in Dubai around 7:30 p.m. on Tuesday.
"He walked to his car in the airport and was not on any ambulance," said Hans, adding that he was accompanied by his doctor and petroleum minister Asim Hussain. Zardari was taken straight to the American Hospital in Dubai, according Hans.
"He's taking rest in the hospital now. He may be there for two to three days," Hans told Reuters.
Zardari traveled to London in September to undergo an angiography and was reportedly given a clean bill of health.
Pakistan's civilian government has been under extreme pressure in recent weeks following the resignation of its ambassador to Washington, Husain Haqqani.
The scandal centers on a memo sent in May to U.S. Adm. Mike Mullen, the Chairman of the Joint Chiefs of Staff at the time, asking for his help in preventing a supposed coup by the Pakistan military, following the covert American raid that killed Osama bin Laden.
Saturday's incident on Pakistan's border with Afghanistan has complicated U.S. attempts to ease a crisis in relations with Islamabad. Senior U.S. officials tell NBC News they have no additional details regarding the US/NATO airstrikes. NBC's Jim Miklaszewski reports.
The operation in a Pakistani garrison town outraged Pakistani officials because they were not told about it beforehand. It also humiliated the military because they were not able to stop it.
Mansoor Ijaz, an American businessman of Pakistani origin, has accused Haqqani of crafting the memo with Zardari's support — allegations both Haqqani and the president have denied.
Tensions between Pakistan's civilian government and military have bedeviled the nuclear-armed South Asian country for almost its entire existence, with the military ruling the country for more than half of its 64-year history after a series of coups.
Relations with the United States have been rocked by a year of bust-ups despite some $20 billion in security and economic aid to Pakistan since 2001, much of it in the form of reimbursements for assistance in fighting militants.
A NATO strike on two Pakistani border posts that killed 24 soldiers on Nov. 26 also infuriated the country's powerful military, which has a tense relationship with Zardari.
The Associated Press, Reuters and msnbc.com staff contributed to this report.
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