Russia is preparing a “concrete plan” for Syria to hand over its chemical weapons, Moscow has said.

Barack Obama has said he will delay a military strike against Syria if the Assad regime agrees to place its chemical weapons under international control.

Russian foreign minister Sergei Lavrov said his country was working on an “effective, concrete” plan for putting Syria’s chemical weapons under international control.

France is to formally put forward a UN Security Council draft resolution for Syria to give up its chemical weapons.

The potential for a diplomatic solution came after Russia proposed that Syria turn its chemical weapons over in return for avoiding strikes from the US.

Russia floated the idea after US Secretary of State John Kerry said the only way for Syria to avoid attack was to hand over all of its chemical weapons in a week.

Prime Minister David Cameron said the Russian plan was “hugely welcome”.

But he warned that it must not become a “distraction” from resolving the crisis over poison gas attacks on civilians in the country.

Iran said it supported the plan and offered to help the Syrian government put the weapons under international control.

China has also said that it backs the plan.

The US State Department had initially attempted to play down the significance of Mr Kerry’s comments, claiming he had been speaking “rhetorically”.

But Mr Lavrov immediately seized on the comments, raising the prospect of international observers supervising the handover.

Syria has welcomed the proposal, but the opposition Syrian National Coalition has called the plan a “political manoeuvre”.

Dozens of scientists would be needed – as part of a team of hundreds – for any inspection, said Sky’s Foreign Editor Tim Marshall.

“You then have to deploy them into a warzone. Who’s going to do that? A lot of these sites are in contested areas.”

On Monday night, with a breakthrough in sight, US Senate majority leader Harry Reid postponed a crucial vote to authorise military action, due to be held on Wednesday.

Mr Obama gave six television interviews with US networks, where he welcomed Syria’s statement as a potentially “positive development”.

Asked by Diane Sawyer of ABC News if he would delay an attack should Mr Assad yield control of his chemical weapons, Mr Obama answered: “Absolutely, if in fact that happened.”

He added: “I want to make sure that norm against use of chemical weapons is maintained.

“That’s in our national security interest. If we can do that without a military strike, that is overwhelmingly my preference.”

He said the US needed to maintain its threat of military action, arguing that any potential breakthrough was due to the sustained pressure on the Assad regime.

In a separate interview with NBC, Mr Obama took the step – unusual for any politician – of conceding he may lose his campaign in Congress for military authorisation.

“I wouldn’t say I’m confident” of the outcome, he said.

Legislation approved in the Senate Foreign Relations Committee last week would give Mr Obama a maximum of 90 days to carry out a military attack.

It includes a ban on combat operations on the ground in Syria.

The US accuses Mr Assad’s government of being behind the August 21 attack in Damascus, which is claimed to have killed up to 1,429 people.

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