An aide to Russian President Vladimir Putin, a close Assad ally, seized on the British no vote as evidence that "people are beginning to understand" the dangers of military action.

U.S. Defense Secretary Chuck Hagel said his country would keep seeking an international coalition to act together on Syria, where hundreds of people were killed in last week's reported chemical attacks. Syria denies using chemical weapons.

"It is the goal of President (Barack) Obama and our government ... whatever decision is taken, that it be an international collaboration and effort," he said.

French President Francois Hollande told the daily Le Monde that he still supported taking "firm" punitive action over an attack he said had caused "irreparable" harm to the Syrian people, adding that he would work closely with France's allies.

Asked if France could take action without Britain, Hollande replied: "Yes. Each country is sovereign to participate or not in an operation. That is valid for Britain as it is for France."

The British parliamentary defeat on Thursday of a government motion on Syria has set back U.S.-led efforts to take military action against Damascus.

Russia fiercely opposes any such action, backing the assertions of Damascus that Syrian rebels were behind the chemical attacks. Putin's senior foreign policy adviser Yuri Ushakov said the British vote reflected majority opinion in Europe. "People are beginning to understand how dangerous such scenarios are," Ushakov told reporters.

Any military strike looks likely to be delayed at least until U.N. investigators report back after leaving Syria on Saturday.

Hollande is not constrained by the need for parliamentary approval of any move to intervene in Syria and could act, if he chose, before lawmakers debate the issue on Wednesday.

"All the options are on the table. France wants action that is in proportion and firm against the Damascus regime," he said.

"There are few countries that have the capacity to inflict a sanction by the appropriate means. France is one of them. We are ready. We will decide our position in close liaison with our allies," Hollande said.

"CORE INTERESTS"

Britain will not join any armed action in Syria after parliament voted 285-272 against a motion by Prime Minister David Cameron to authorize a military response in principle.

British Defence Secretary Philip Hammond acknowledged that the United States would be disappointed that its close ally would not be involved, but said: "I don't expect that the lack of British participation will stop any action.

U.S. officials suggested Obama would be willing to proceed with limited actions against Syria even without allied support.

"President Obama's decision-making will be guided by what is in the best interests of the United States," White House spokeswoman Caitlin Hayden said in a statement after the British vote. "He believes that there are core interests at stake for the United States and that countries who violate international norms regarding chemical weapons need to be held accountable."

In a briefing with senior lawmakers on Thursday, Obama administration officials said they had "no doubt" Assad's government had used chemical weapons, U.S. Representative Eliot Engel, who joined the call, told Reuters.

Cameron said he would not override the British parliament. "I strongly believe in the need for a tough response to the use of chemical weapons, but I also believe in respecting the will of this House of Commons," he said after a vote that reflected misgivings stemming from Britain's role in the 2003 Iraq war.

NO SMOKING GUN

U.S. officials acknowledged on Thursday they lacked proof that Assad personally ordered last week's poison gas attack, and some allies have warned that military action without U.N. Security Council authorization may make matters worse.

On the call with lawmakers, U.S. officials, including Hagel and Secretary of State John Kerry, cited evidence of chemical weapons use including "intercepted communications from high-level Syrian officials", said Engel, the top Democrat on the House of Representatives Foreign Affairs Committee.

After the 90-minute briefing, some lawmakers said the administration still had work to do to convince the public.

"The president is going to have to make his case, I think, to the American people I think before he takes any action," said Republican Howard "Buck" McKeon of California, chairman of the House Armed Services Committee.

Expectations of imminent turmoil eased as the diplomatic process was seen playing out into next week, and the White House emphasized that any action would be "very discrete and limited", and in no way comparable with the Iraq war.

Syrian opposition sources said Assad's forces had removed several Scud missiles and dozens of launchers from a base north of Damascus, possibly to protect them from a Western attack, and Russia was reported to be moving ships into the region.

Syria says rebels perpetrated the gas attacks, a version dismissed by Washington and its allies.

U.N. chemical weapons inspectors visited a military hospital in a government-held area of Damascus on Friday to see soldiers affected by an apparent chemical attack, a Reuters witness said.

The inspectors have spent the week visiting rebel-controlled areas on the outskirts of Damascus affected by gas attacks.

Witnesses said the investigators were meeting soldiers at the Mezze Military Airport who state media said were exposed to poison gas after finding chemical agents in a tunnel used by rebels in the Damascus suburb of Jobar last Saturday.

CHINA OPPOSES HASTY U.N. ACTION

The United Nations says the team will leave Syria on Saturday and report to Secretary-General Ban Ki-moon.

France and Germany urged the world body to pass its report to the Security Council as soon as possible "so that it can fulfill its responsibility with regards to this monstrous crime".

The United States, Britain and France have said action could be taken with or without a Security Council resolution, which would probably be vetoed by Russia. But some countries are more cautious: Italy said it would not join any military operation without Council authorization.

Western diplomats say they are seeking a vote in the 15-member Council to isolate Moscow and demonstrate that other countries are behind air strikes.

A report from Moscow that Russia is sending two warships to the eastern Mediterranean underscored the complications around even a limited military strike, although Russia has said it will not be drawn into military conflict.

Ambassadors of the five veto-wielding permanent Security Council members - the United States, Russia, China, Britain and France - have discussed a draft resolution that would authorize "all necessary force" in response to the alleged gas attack, but made no progress on Thursday, a council diplomat said.

China said there should be no rush to force council action against Syria until the U.N. inspectors complete their work.

"Before the investigation finds out what really happened, all parties should avoid prejudging the results, and certainly ought not to forcefully push for the Security Council to take action," Foreign Minister Wang Yi told Ban in a phone call, Xinhua reported.

"A political resolution is still the only way out," he said.

The International Committee of the Red Cross joined a chorus of voices urging caution, saying further escalation would force more Syrians to flee and worsen the plight of civilians.

According to the U.S. national security officials, evidence that forces loyal to Assad were responsible goes beyond the circumstantial to include electronic intercepts and some tentative scientific samples from the site.

"This was not a rogue operation," one U.S. official said.

In Damascus, residents and opposition forces say Assad's forces appeared to have evacuated most personnel from army and security command headquarters in the centre as a precaution.

People unable to decide whether to leave for neighboring Lebanon said the border was already jammed.

"We're hearing people are spending hours - like 12 or 14 hours - waiting in line at the border," said Nabil, who was considering leaving town for Beirut with his wife and young daughter, "just until the strike is over".

(Additional reporting by Matt Spetalnick, Andrea Shalal-Esa, Patricia Zengerle, Steve Holland, Thomas Ferraro and Jeff Mason in Washington, Erika Solomon and Oliver Holmes in Beirut, Khaled Yacoub Oweis in Amman, Sarah Marsh in Berlin, Timothy Heritage in Moscow, Phil Stewart in Manila, Louis Charbonneau and Michelle Nichols at the United Nations and Andrew Osborn, Marie-Louise Gumuchian and Peter Apps in London; Writing by Alistair Lyon; editing by David Stamp)