London: The UK government is under growing pressure to consider a second parliamentary vote on military action against Syria.
The US has announced that hair and blood samples prove the regime of Syrian President Bashar al Assad has used sarin gas to attack civilians, indicating that the case for military strikes is growing.
It has, however, delayed strikes pending the approval of Congress next week.
But Britain`s Deputy Prime Minister, Nick Clegg, ruled out a re-vote on the issue after the British Parliament had defeated a government motion for military action last week.
"We did it last Thursday, the answer was very clear, it was not the answer I was hoping for," he said here today.
"I personally think there was a case for Britain, on humanitarian grounds, to participate in deterrent action to stop the further use of these abhorrent and illegal weapons but Parliament did not agree and I think there is no point to keep asking the same question," he added.
Earlier, London Mayor Boris Johnson said a new motion could be debated if "better evidence" of chemical attacks emerges.
"If there is new and better evidence that inculpates Assad, I see no reason why the government should not lay a new motion before Parliament, inviting British participation and then it is [Opposition leader] Ed Miliband, not [Prime Minister] David Cameron, who will face embarrassment," Johnson wrote in the `Daily Telegraph`.
Cameron had been forced to rule out the use of British force in Syria following a defeat in the House of Commons.
UK foreign secretary William Hague has now stressed that Britain will only offer diplomatic support to its allies.
"Parliament has spoken. I don`t think it is realistic to think that we can go back to Parliament every week with the same question having received no for an answer," he said.
Russia has said that US strikes on Syria would delay a peace conference "for a long time, if not forever", and has sent a spy ship to the Mediterranean late on Sunday.
Meanwhile, the rhetoric between Washington and the Syrian regime has grown increasingly hostile in recent days.
US President Barack Obama has launched an intense lobbying effort in an attempt to sway sceptical US politicians to support a military strike.
According to US estimates, up to 1,429 people, including at least 426 children, were killed in the alleged chemical attack in Damascus last month.