A Russian official has said for the first time that the Syrian government may be defeated by opposition forces, BBC News reported.

President Bashar al-Assad's forces are "losing more and more control and territory", deputy foreign minister Mikhail Bogdanov said on Thursday, December 13.

Russia was also making plans for a possible evacuation of thousands of its citizens in Syria, Mr Bogdanov said.

Russia has been one of the staunchest international allies of Mr Assad's government.

"Unfortunately, we cannot rule out the victory of the Syrian opposition," Mr Bogdanov said.

Russia, along with China, has used its veto at the UN Security Council to block resolutions condemning the Syrian government's use of violence.

Later on Thursday, Nato's Secretary General Anders Fogh Rasmussen said the organisation believed the Syrian government was approaching collapse.