The Deputy Prime Minister has said he "can't foresee any circumstances" where there would be a second vote on military action in Syria.

Nick Clegg spoke after London Mayor Boris Johnson said fresh evidence against the Assad regime could allow the Government to go back to Parliament.

US secretary of state John Kerry has revealed the United States has evidence of sarin gas use after testing samples of hair and blood and insisted he is confident that Congress will back military action when it is put to a vote next week.

Prime Minister David Cameron has ruled out the use of British force following a humiliating defeat in the Commons but the prospect of Parliament revisiting the issue was raised following US president Barack Obama's announcement that he is seeking congressional support for a punishment strike.

But Mr Clegg said: "We're not going to keep asking the same question of Parliament again and again. We live in a democracy, the executive cannot act in a way which clearly is not welcome to Parliament or the British people, so we're not proposing to do so." He added: "I can't foresee any circumstances that we would go back to Parliament on the same question, on the same issue."

Mr Johnson has become the latest figure to suggest that British forces could still be deployed following the atrocity on the outskirts of Damascus, insisting there was "no reason" why a renewed bid for parliamentary support could not still be made.

Mr Clegg, who was in favour of military action in the Middle Eastern country, also accused Labour of using last week's House of Commons vote to score "party political points", after the Government was defeated.

He said: "I don't think anyone should pretend that deciding to enter into military action to deter the further use of chemical weapons is simple. It's not simple, it's not straightforward. My own view is that the Labour Party seemed to take this as an opportunity to score party political points as much as rise to the challenge and the gravity of the issue.

"From time to time there are just issues - and this is clearly one of them - where I actually don't think the British people are particularly interested in political point-scoring at Westminster. They really just want their representatives to look at it in Parliament in a sober and thoughtful way, which is by and large what happened last Thursday in the debate."

Mr Clegg's comments came after the US said it had uncovered fresh evidence of sarin use in Syria. The deadly nerve agent is thought to have been behind the chemical attacks in the country on August 21.