The Syrian government has guaranteed Russia that it will not use or move its stockpiles of chemical weapons, the Russian foreign ministry's point man on Syria has said.
Speaking in an interview with The Associated Press on Thursday, Gennady Gatilov, the Russian deputy foreign minister, said that Moscow was working closely with Damascus to make sure its arsenal of chemical weapons remained securely in place.
The statement follows a warning from US President Barack Obama earlier this week that Washington might be forced to intervene in the Syrian civil war if the Damascus government were to utilise or move such weapons of mass destruction.
Damascus has said it might use its chemical weapons if attacked by outsiders, although not against its own people.
But some have activists have accused government forces of using chemical weapons to attack opposition-controlled cities and towns in its bid to crush the country's 17-month popular uprising. The reports can not be confirmed due to restrictions on foreign journalists.
Gatilov said: "We have received from them [Syria] very clear assurances that the Syrian government will do everything in its power to prevent this from happening, so that chemical weapons securely stay where they are now. We were assured that very serious control is being applied to ensure the preservation of these weapons and that now there is no threat that something might happen to them, taking the situation out of control."
He added that Moscow is in full agreement with Washington on the need to prevent Syria's chemical weapons from being used.
"The situation getting out of control is fraught with most serious complications not just for Syria, but also for the entire region," said Gatilov.
As Syrian opposition fighters gain control over cities and towns across the country, there are rising fears that government forces will use chemical weapons in its bid to crush the uprising, a move that would impact civilian areas.
"This is totally new territory historically. Never in history has a WMD-armed country fallen into civil war," said Charles Blair of the Federation of American Scientists.
"This has never happened," he told AFP.
"We don't have perfect visibility to all the chemical weapons sites but we have very effective ways of monitoring chemical stockpiles," said a senior official, who spoke on condition of anonymity.
As the US monitors the chemical arsenal with the help of spy satellites, officials have to take into account "whether the regime intends to use it, whether it falls into the wrong hands and whether there's a collapse of security around the sites", according to the official.
Syria's chemical weapons stockpile, which dates back to the 1970s, is the biggest in the Middle East, but its precise scope remains unclear, according to analysts.
Syria has hundreds of tonnes of various chemical agents, including sarin and VX nerve agents, as well as older blistering agents such as mustard gas, dispersed in about 50 manufacturing and storage sites, experts say.