"Countries who violate international norms regarding chemical weapons need to be held accountable," the US said. Washington accuses Syrian government forces of using chemical weapons – a claim denied by Damascus.
The United States is still seeking an "international coalition" in response to Syria\’s alleged use of chemical weapons, despite a vote against military action by British MPs, Defence Secretary Chuck Hagel said Friday.
"Our approach is to continue to find an international coalition that will act together," Hagel said in Manila, a day after Britain\’s lower house of Parliament rejected a motion for British participation in a military strike.
British Prime Minister David Cameron has lost his parliamentary vote calling for military action over Syria "in principle".
Cameron said it was clear the British Parliament does not want action and "I will act accordingly".
The government motion was defeated 285 to 272, a majority of 13 votes.
It effectively rules out British involvement in any US-led strikes against the Assad regime.
Reacting to the British vote, Hagel said “First every nation has the responsibility to make their own decisions. And we respect that with any nation. We are continuing to consult with the British as we are with all of our allies and partners. And that consultation includes ways forward, together on a response to this weapons attack in Syria."
U.S. lawmakers have asked the White House and State Department to justify a possible U.S. military strike against Syria.
Members of Congress briefed by senior Obama administration officials Thursday said there is no doubt the Syrian government carried out a chemical weapons attack last week.
Democratic Representative Eliot Engel of New York said the U.S. officials cited intercepted communications between senior Syrian officials. Engel also said intelligence showed the Syrians moved materials around in advance of a chemical strike.
In Thursday\’s statement, the White House also stressed that it would "continue to consult" with the UK over Syria, describing London as "one of our closest allies and friends".
President Barack Obama is still deciding how to respond to Syria. A military strike against the Assad government appears to be the most likely course of action.
Syria denies carrying out a chemical attack and accuses the rebels of using such weapons on Syrian soldiers
At least 355 people are reported to have died in a suspected chemical attack in the Ghouta area – on the outskirts of the capital, Damascus – on 21 August.
United Nations Secretary-General Ban Ki-moon has urged world powers to hold off on possible military action until a U.N. chemical weapons inspection team completes its work in the country.
U.N. spokesman Farhan Haq on Thursday said the team investigating the August 21 attack near Damascus would leave the country by Saturday morning. While some will remain in Europe to analyze their samples, Haq said U.N. disarmament chief Angela Kane and other inspectors will be in New York in the coming days to brief Ban.
“They will have a large number of facts at their disposal, they’ve collected considerable amount of evidence – evidence through samples, evidence through witness interviews — they can construct from that a fact-based narrative that can get at the key facts of what happened,” he said.
Once laboratory results are in, the team will issue a final report. Haq said, “It is imperative that the work that the investigation team does be seen by all as fair, impartial and accurate.”
Earlier on Thursday, the five permanent UN Security Council members held a short meeting, but diplomats said their views remained "far apart". Talks with Britain, China, France and the United States lasted about 45 minutes, but diplomats did not brief reporters on what transpired.
China and Russia have blocked previous attempts at the U.N. to impose sanctions on President Assad’s regime. That has led to frustration for the U.S. and its European allies.
Iranian President Hassan Rouhani has said his government and Russia will work to prevent an attack on Syria, and warned any assault could “bring great costs” to the region.
Iran also has warned that any Western action against Syria would result in the “imminent destruction of Israel,” a U.S. ally in the region.
Also Thursday, Canadian Prime Minister Stephen Harper said his government supports Washington and its other allies contemplating a military response to Syria. He said, however, the Canadian military would not take a role in any attack.
In Paris, French President Francois Hollande has said his country is ready to punish those responsible for using chemical weapons. But he has not yet said whether the French will join the United States.
More than 100,000 people are estimated to have died since the conflict erupted in Syria in March 2011, and the conflict has produced at least 1.7 million refugees.