"We, for our part, have already worked with the Syrian government and have raised this issue. We have been given very strong assurances that everything possible will be done to stop it happening. Guarantees were also given that the chemical weapons will remain in their current place," Gatilov said in an interview published on the Russian Foreign Ministry's website on Friday.

"They assured us that very serious control is being exercised over the safety of these weapons, and there is no threat today that something could happen to them or the situation could get out of control," the Russian diplomat said.

Moscow does not know for certain whether Washington's control over Syria's opposition forces is serious enough to prevent weapons of mass destruction from falling into their hands, Gatilov said.

Interfax