Sherman's visit came ahead of talks in Paris on Monday between US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov that are due to focus on Moscow's push to give Iran a formal seat at the so-called Geneva 2 negotiations.

Sherman did not address reporters after her meeting with Russian Deputy Foreign Ministers Mikhail Bogdanov and Gennady Gatilov, Moscow's two representatives at the Syria conference that is scheduled to begin January 22 in Switzerland.

But the Russian foreign ministry said the two Moscow diplomats told Sherman that Assad's campaign against "terrorist groups" deserved comprehensive support.

"The Russian representatives stressed the importance of uniting efforts by the Syrian government and the patriotically-inclined opposition to fight terrorist groups whose activities are threatening not only the future of Syria, but also regional stability," the Russian foreign ministry said in a statement.

The Russian statement said the two sides agreed that the Geneva 2 conference must focus on engaging government and opposition members in their first direct talks.

"The forum must give the start to direct Syrian talks based on the Geneva communique, whose frameworks call on the Syrians themselves to decide the issue of how their future government works," the Russian statement said.

The July 2012 talks concluded with an agreement that Assad and his opponents should decide on a transitional government whose representatives suited all sides.

US officials interpreted the wording to mean that the deal excluded the possibility of Assad remaining in power.

But Russia insists that Assad cannot be forced to step down through outside pressure because he retains strong domestic support.

NJF/NJF