U.S. Secretary of Defense Leon Panetta said Thursday that intelligence about Syrian chemical weapons "raises serious concerns" that the regime of Bashar Assad may use them against the country's own citizens.

"The whole world is watching, the whole world is watching very closely," Panetta said. "And the president of the United States has made it very clear, there will be consequences — there will be consequences if the Assad regime makes the terrible mistake by using these chemical weapons on their own people."

His comments came a day after U.S. officials told NBC News that the Syrian military had loaded the precursor chemicals for sarin, a deadly nerve gas, into aerial bombs that could be dropped from dozens of fighter-bombers. The defense chief, who was speaking at a news conference at the Department of Veterans Affairs, would not elaborate on what the potential consequences would be. 

A member of the regime in Damascus, however, dismissed the assertions Thursday, saying he feared the United States and other Western powers could be trying to find a "pretext for intervention" in Syria's civil war, Reuters reported.

Sarin is an extraordinarily lethal agent. Iraqi President Saddam Hussein's forces killed 5,000 Kurds with a single sarin attack on Halabja in 1988.

Assad's deputy foreign minister Faisal Maqdad said Thursday that they would never kill Syrians with chemical weapons, dismissing the Western intelligence reports as "theater."

"Syria stresses again, for the tenth, the hundredth time, that if we had such weapons, they would not be used against its people. We would not commit suicide," Maqdad said, according a Reuters report that cited his comments on Lebanon's Al Manar television, the voice of the pro-Assad Hezbollah movement.

"In fact, we fear a conspiracy ... by the United States and some European states, which might have supplied such weapons to terrorist organizations in Syria, in order to claim later that Syria is the one that used these weapons," he added.

"We fear there is a conspiracy to provide a pretext for any subsequent interventions in Syria by these countries that are increasing pressure on Syria," he said.

Aref Hretani / Reuters

Children run along a street damaged by what activists said was a Syrian Air Force airstrike in the Aleppo district of Salaheddine on Wednesday.

Panetta echos Obama 'red line' warning
"The intelligence we have raises serious concerns"  that Damascus was considering using chemical weapons, Panetta said Thursday.

"Without commenting on the specific intelligence ... we remain very concerned, very concerned that as the opposition advances, in particular on Damascus, that the regime might very well consider the use of chemical weapons." 

Obama and other NATO leaders have warned that using chemical weapons would cross a red line and have consequences, which they have not specified.

Four U.S. Senators on Thursday urged President Obama to send a strong message to Assad.

"We urge the President of the United States to make whatever military preparations are necessary to show Assad that the United States is fully willing and able to impose the consequences that he has spoken of in the event these weapons are used," said Sen. John McCain (R-Ariz), speaking first. "For deterrence to work it must be based on a credible threat."

He appeared with Sen. Joseph Lieberman (I-Conn.), Sen. Chris Coons (D-Del.) and Sen. Lindsay Graham (R-S.C.).

"We are all saying to President Obama, who has stated that there will be drastic consequences for Assad and his government if they use chemical and biological weapons, we’re with you," said Lieberman. "There’s strong support across Congress if the president takes the strong action that’s necessary to prevent a very, very — historically horrific — humanitarian disaster in Syria. 

There are limited options for military intervention by the United States in Syria. It has one of the most robust air defense systems in the world — supplied by key ally Russia — but one option could be sending cruise missiles to attack regime targets.

Germany's cabinet approved stationing Patriot anti-missile batteries on Turkey's border with Syria, a step requiring deployment of NATO troops that Syria fears could permit the imposition of a no-fly zone over its territory.

Slideshow: Syria uprising
Syria loads chemical weapons into bombs; military awaits Assad's order
Syria regime 'reeling, armed to the teeth' with chemical weapons
More weapons in Syria could trigger 'all-out war'

The 20-month-old battle between Assad and opposition forces has claimed more than 40,000 lives.

U.S. Secretary of State Hillary Clinton met in Dublin on Thursday with Russian Foreign Minister Sergei Lavrov and international Syria mediator Lakhdar Brahimi to try to restart a U.N. peace process for Syria. Prior to the meeting, she said she expected to raise the chemical weapons threat.

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Clinton has said that in addition to the possible use of chemical bombs by "an increasingly desperate" Assad, Washington was concerned about the government losing control of such weapons to extreme Islamist armed groups among the rebel forces.

U.S. officials said Washington was considering blacklisting Jabhat al-Nusra, an influential rebel group accused by other rebels of indiscriminate tactics that has advocated an Islamic state in Syria and is suspected to have ties to al-Qaida.

In other developments reported by Reuters:

• Syrian state TV said a\n explosion in front of the Damascus headquarters of the Syrian Arab Red Crescent killed at least one person on Thursday.
• Activists said the army pummeled several eastern suburbs of Damascus, where the rebels are dominant, with artillery and mortar fire. The suburbs have been cut off from the city's water and electricity for weeks, rebels say, accusing the government of collective punishment.
• Rebels say they have surrounded an air base two-and-a-half miles from the center of Damascus, a fresh sign the battle is closing in on the Syrian capital.
• Rebels said they were battling soldiers on the road to Damascus International Airport, 12 miles out of the capital, where several airlines have canceled flights due to security concerns.

Maqdad, in his interview on Thursday, argued that reports of such advances were untrue. "What is sad is that foreign countries believe these repeated rumors," he said. Rebel and state claims about the military situation cannot be verified independently. But residents inside the capital say the sound of shelling on the outskirts has become a constant backdrop. 

Reuters contributed to this report.

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