France will put a resolution to the UN Security Council to place Syria's chemical weapons under international control so they can be destroyed, Foreign Minister Laurent Fabius says.
He said the resolution would threaten "extremely serious" consequences if Syria breached its conditions.
The move follows Russia's announcement of a plan to put the chemical weapons under international control.
Syria has said it accepts the Russian proposal, though details are sketchy.
"We held a very fruitful round of talks with [Russian] Foreign Minister Sergei Lavrov yesterday [Monday], and he proposed an initiative relating to chemical weapons. And in the evening, we agreed to the Russian initiative," Russian news agency Interfax quoted Syrian Foreign Minister Walid Muallem, who is in Moscow, as saying.
This would "remove the grounds for American aggression", he said.
Earlier, Mr Fabius, who was speaking at a news conference in Paris, said the resolution, based around five points, would demand that Syria "bring fully to light" its chemical weapons programme.
The measure would also set up international inspections and controls of the dismantling process.
The resolution would be tabled under Chapter 7 of the UN charter covering possible military and non-military action to restore peace, Mr Fabius added.
The plan had been discussed before, he said, but had probably been advanced by the pressure applied in recent weeks.
The Russians have blocked all previous French-led efforts at the Security Council, says the BBC's Christian Fraser in Paris.
Both France and the United States are wary of an Iraq-style game of cat and mouse - but they are prepared to give the Moscow-backed plan a chance, our correspondent adds.
What the French are keen to avoid, Mr Fabius said, is a plan that is only there as a delaying tactic, which is why all options, including the threat of a strike, will remain on the table, our correspondent says.
On Tuesday, the Arab League signalled its support for the Russian initiative.
Its head, Nabil al-Arabi, said the League had always backed a political solution.Obama sceptical
There have been few details so far of Russia's plan, but Mr Lavrov said in Moscow that it was "preparing a concrete proposal which will be presented to all interested sides, including the US... a workable, specific, concrete plan".
Mr Muallem said: "We are convinced that the position of those striving for peace is much stronger than that of those trying to fuel war."
Mr Lavrov said he had spoken to US Secretary of State John Kerry on the telephone about the plan on Monday.
Mr Lavrov said the Russian initiative was "not a purely Russian initiative... It grew out of contacts we've had with the Americans".
Russian President Vladimir Putin and US President Barack Obama discussed the idea on the sidelines of a G20 summit last week, Mr Putin's spokesman said on Tuesday.
Mr Lavrov noted Mr Obama's suggestion in a US TV interview that this may be a "breakthrough".
Overnight, Mr Obama said the Russian proposal could be a breakthrough. He is to hold working lunches with senior senators on Tuesday and his prime time television address is still scheduled to go ahead in the evening.
The White House said Mr Obama still planned to use the address to argue that Congress should authorise the use of force if required.
Spokesman Jay Carney said there were ample reasons to be sceptical about how serious Syria was on implementing the Russian plan.
"Before this morning, the Syrian government had never even acknowledged they possessed chemical weapons. Now they have,'' Mr Carney said in an interview on MSNBC.
The US Senate had been expected to vote this week on a resolution authorising military force, but the Russian plan has led to a postponement.
Republican Senator John McCain, who has been an advocate of military action, said on Tuesday that a bipartisan group of senators was now working on a new resolution that would set Syria a specific period of time to turn over its chemical weapons.
Senator McCain told CBS he was "extremely sceptical" about the Russian proposal but that "to not pursue this option would be a mistake".
Opinion polls suggest that a majority of voters are opposed to Mr Obama's calls for intervention in Syria.
According to a survey by the Associated Press news agency, 61% of Americans want Congress to vote against authorisation for military strikes.
The US claims that Mr Assad's forces carried out a chemical attack in Damascus on 21 August, killing 1,429 people.
Mr Assad's government blames the attack on rebels fighting to overthrow him, in a conflict that the UN says has claimed some 100,000 lives.
Watch President Obama's address to the nation live on the BBC News website at 21:00 EDT on Tuesday (01:00 GMT/02:00 BST Wednesday).