Russia has claimed that forces loyal to Syrian president Bashar al-Assad are battling al-Qaida-backed terrorists, including at least 15,000 foreign fighters.

Russia's deputy ambassador, Mikhail Lebedev, said government troops were protecting Syrian infrastructure, including schools and hospitals, from large-scale attacks by rebel forces backed by al-Qaida.

Lebedev told Reuters the information about al-Qaida links in Syria was an "unambiguous fact" but declined to say if Russia would provide the UN with evidence to back its allegation that Syrian rebels were committing torture.

"Rebel groups attack, kill, torture and intimidate the civilian population. The flow of all kind of terrorists from some neighbouring countries is always increasing," Lebedev told a humanitarian forum on Syria at the United Nations in Geneva.

His claim came after state television in Syria and Iran showed footage from Homs in which foreign currency was found on terrorists, who had been accused of attacking the Baba Amr district of Homs. The broadcast said the currency proved that rebel groups were receiving foreign support.

On closer examination, however, the banknotes were discovered to have been withdrawn from circulation 30 years ago.

Bloggers and activists took to Twitter to expose the subterfuge. Beirut-based activist Shakeeb al-Jabri said that some of the bills described as "Israeli banknotes" were in fact Lebanese liras that have not been in use since 1985.