President Barack Obama said on Monday that he would put planned air strikes of Syria on hold if the regime of Bashar al-Assad followed a Russian proposal to hand over control of the country’s chemical weapons stocks.

Mr Obama’s comments capped a day of fast-moving diplomatic manoeuvres which appears to start with a misstatement by US secretary of state John Kerry and ended with a proposal that could provide a way out from deeply unpopular military action against Syria.

Asked by ABC if he would hold off on air strikes were Syria to relinquish control of its chemical weapons, Mr Obama said: “Absolutely. If in fact that happens.”

In a separate interview with CNN, one of six he gave on Monday, Mr Obama said “it is possible that we can get a breakthrough but we do not want this to be just a stalling or delaying tactic”. The US would “engage with Russia” to see if they were able to reach an agreement that was “enforceable and serious”.

Mr Obama was speaking hours after Russia launched an unexpected diplomatic initiative to defuse the Syrian crisis when it called on the Assad regime to place its chemical weapons stockpile under international supervision.

In a move that took western diplomats by surprise, Sergei Lavrov, Russia’s foreign minister, announced that Moscow had proposed to the Assad regime that it should “not only put its chemical weapons storages under international control but also have them destroyed subsequently”.

At a press conference in Moscow, Mr Lavrov said: “If the establishment of international control over chemical weapons in that country will avoid strikes, we will immediately begin working with Damascus.”

Russia’s move created an unexpected twist in the Syria crisis, coming days before the US Congress was due to start voting on plans for a US missile strike on the Assad regime as punishment for last month’s chemical attack in Damascus. Mr Obama’s comments suggested that the congressional votes could be delayed as a result of the Russian proposal.

The idea began to circulate on Monday after an offhand comment from Mr Kerry, who said the Assad regime could avoid a military strike by handing over its stock of chemical weapons. He said they were unlikely to do this and the state department immediately issued a statement describing Mr Kerry’s remarks as “rhetorical”.

However, within hours, Mr Lavrov had suggested that Syria should join the Organisation for the Prohibition of Chemical Weapons, the monitoring agency which controls worldwide chemical stocks. He said he expected “a quick and, I hope, a positive, answer”.

He made the announcement after meeting Syria’s foreign minister Walid Mouallem. Mr Lavrov did not spell out Russia’s proposal in detail or which states would be involved in protecting or monitoring Syrian chemical stocks.

Mr Mouallem told reporters that Syria welcomed the initiative. But he stopped short of saying the regime would agree to carry it out, arguing Russia was “attempting to prevent American aggression against our people”.

Any agreement to establish international monitoring of Syria’s chemical weapons stockpile would amount to a huge strategic concession by Mr Assad, who is fighting to consolidate power in Syria. Western diplomats will also fear that a protracted negotiation to try and reach an accord could be a tactic by Syria to delay a US strike against the Assad regime.

In its initial reaction, the Obama administration played down the prospect of any discussions over Syria’s chemical weapons stockpile. Jen Psaki, a state department spokeswoman, said Mr Assad was a “brutal dictator with a history of playing fast and loose with the facts” and that he “cannot be trusted to turn over chemical weapons otherwise he would have done so long ago”.

In London, David Cameron, Britain’s prime minister, said: “We have to be careful to make sure this is not a distraction tactic. But if it’s a genuine offer, it should be genuinely looked at.”

However in New York, Ban Ki-moon, the UN secretary-general, was quick to throw his weight behind the Russian move, saying he might ask the UN Security Council to demand that Syria destroy its chemical stocks. “I’m considering urging the Security Council to demand the immediate transfer of Syria’s chemical weapons and chemical precursor stocks to places inside Syria where they can be safely stored and destroyed,” he said.

France, which has pledged to join any US military strike on Syria, said the Russian proposal “merits close consideration” but set three conditions. Laurent Fabius, foreign minister, said Mr Assad had to put his chemical weapon arsenal under international control for destruction without delay; the UN Security Council should pass a resolution setting a short timetable and “firm consequences” if Syria did not comply; and those responsible for the attack on August 21 must be brought before the International Criminal Court.

Mr Lavrov unveiled his proposal on a day that saw growing tensions between the US and Syria over the possibility of a US-led air strike. Mr Obama is entering several days of intense lobbying of Congress amid signs that the White House faces an uphill struggle to get backing for a strike on Syria.

In Damascus, meanwhile, Mr Assad warned on Monday that the US could “expect every action” in retaliation if it were to implement punitive missile strikes against his country, warning that the US would “pay the price”.

Mr Assad said the US should expect “repercussions somewhere else, in different forms” if it were to hit Syria. Such responses, he said in an interview with the US broadcaster PBS, could be “direct and indirect”, without elaborating what that meant.