The UN-Arab League's Syria envoy is meeting with senior U.S. and Russian officials to explore prospects of bringing Syria's warring sides for peace talks in Geneva, the Associated Press reports.

Previous attempts to bring the two sides together have failed mainly because of disputes over who should represent the Syrian opposition and government, and whether Iran, Saudi Arabia and other regional powers should be at the table.

Envoy Lakhdar Brahimi is holding closed-door meetings Monday with Russian Deputy Foreign Ministers Mikhail Bogdanov and Gennady Gatilov, whose country is Syria's main ally, and U.S. Under Secretary of State for Political Affairs Wendy Sherman.

Recent battlefield victories have shifted the momentum of Syria's nearly three-year conflict in Syrian President Bashar Assad's favor.