Moscow: Russia is concerned by the prospect of Syrian chemical weapons falling into terrorist hands, Deputy Foreign Minister Mikhail Bogdanov said Thursday.
"The greatest danger is that parts of Syria continue to fall under the control of the opposition where extremists, terrorists, and Al Qaeda have strong positions," he said.
"That could have very serious consequences."
"Everyone is afraid of that, including our American partners," he said, adding that militants are already gaining control of military arsenals on the ground, including anti-aircraft missiles.
That could also happen to chemical weapon stockpiles, Bogdanov said.
"This has already happened in Aleppo with the seizure of a plant manufacturing chemical components that can be used for terrorist purposes," he said.
The Syrian authorities have assured Moscow that they will not use chemical weapons against rebel forces.
Syria has not signed the international Chemical Weapons Convention and is believed to possess mustard gas and sarin, an extremely toxic nerve agent.
The CIA says Syria has had a chemical weapons programme "for years" and that the weapons can be "delivered by aircraft, ballistic missile, and artillery rockets".
But Syria has never deployed the weapons, although it warned this summer that they could be used against "foreign invaders".
Western powers have warned President Bashar al-Assad that any use of chemical weapons would be unacceptable.
US President Barack Obama has told Syria that the movement or use of chemical weapons would have "enormous consequences".
The Syrian conflict has claimed around 40,000 lives since the uprising against Assad started in March 2011.
Russia, along with China, has drawn heavy Western criticism for its refusal to support UN sanctions against Assad`s regime. Moscow said the proposed UN resolutions in fact betrayed a pro-rebel bias and would do nothing to bring peace.