US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov have met in Geneva to discuss how to locate and destroy the Syrian chemical weapons arsenal.
US officials have described Russia's plan as "doable but difficult."
The talks were held apart from the United Nations which so far has had no formal role in the proposal.
A contentious French resolution threatening military action has not, however, been withdrawn but is still on the table at the UN security council.
Syria's President Bashar al-Assad appeared on Russian TV to confirm that the weapons will be placed under international control.
Mr Assad said this was a reaction to the Russian initiative and not the threat of US military action.
The rebel Free Syrian Army has issued a strong rejection of the Russian proposal.
FSA military commander General Selim Idriss said: "The Free Syrian Army announces its categorical rejection of the Russian initiative that foresees placing chemical weapons under international control."
He said that world powers should not "be satisfied only by removing the chemical weapon, which is the tool of a crime, but judge the author of the crime before the International Criminal Court."
The Syrian National Coalition opposition group attacked the initiative as a "political manoeuvre aimed at buying time."
Gen Idriss also called on countries backing the 30-month uprising against President Assad to increase the supply of arms to the rebels, telling the US National Public Radio that they had received no such aid.
But US officials insisted that the CIA had been delivering light machine guns and other weapons to Syrian rebels for several weeks.
According to senior US intelligence figures the agency also arranged the delivery of anti-tank weaponry such as rocket-propelled grenades through a third party, presumably one of the Gulf countries that has also been arming the rebels.
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