US President Barack Obama warned President Assad this month he would face "consequences" if chemical weapons were turned on the Syrian people
Syria has acted to consolidate its chemical weapons into "one or two" places to prevent rebels from capturing them, Russia's foreign minister says.
Sergei Lavrov said the weapons had previously been "scattered" across the country and they were "under control" for the time being.
Mr Lavrov also said President Bashar al-Assad had no plans to leave Syria.
Rebels have been fighting the Assad government for 21 months. Activists say some 44,000 people have been killed.
Meanwhile in Syria on Saturday, activists said a car bomb had exploded in an eastern district of the capital, Damascus, killing at least five people.
'Not going anywhere'
Mr Lavrov told journalists on a flight returning to Moscow from an EU-Russia summit in Brussels: "According to the information we have, as well as the data of the US and European special services, the [Syrian] government is doing everything to secure [its chemical stockpiles].
"The Syrian government has concentrated the stockpiles in one or two centres, unlike the past when they were scattered across the country."
Mr Lavrov said the biggest threat from Syria's chemical weapons would be if militants managed to capture them.
The US fears Syria may be tempted to use the weapons if its situation becomes more desperate.
Mike Rogers, the chairman of the US House Committee on Intelligence, told the BBC a regional plan was needed to secure the weapons "immediately".
"If not, we're going to have a very major destabilising event in the region," Mr Rogers said.
US President Barack Obama warned President Assad this month he would face "consequences" if chemical weapons were turned on the Syrian people, saying it would be "totally unacceptable".
The US has said this would be a "red line" that might trigger military intervention.
Mr Lavrov said he believed Western powers had no appetite to intervene.
"I have the feeling that they are praying for Russia and China to continue blocking permission for external intervention. Because if there is such a decision, they will have to act, and no-one is ready to act."
Mr Lavrov said he believed neither side could win the civil war, and that President Assad was not going to leave.
"Assad is not going anywhere, no matter what anyone says, be it China or Russia," Mr Lavrov said.
He said some regional powers had asked Moscow to mediate for Mr Assad to leave.
Mr Lavrov said he told them: "Why do we have to do it? If you have these plans, go to him yourselves."
Inside Syria, the UK-based opposition activist group, the Syrian Observatory for Human Rights, said a car bomb had exploded in the eastern Damascus district of Qaboun, killing at least five people and injuring dozens.
It also reported that rebel forces had warned two predominantly Christian towns they could come under attack.
The rebels said the towns of Mahrada and Sqailbiyeh in Hama province were being used by government forces to launch attacks.
The Observatory also said there were clashes between rebels and government forces in the south of the capital, in the Hajar al-Aswad district.
The Observatory says more than 44,000 people have been killed in the past 21 months of unrest, including nearly 31,000 civilians.