More than 160 killed as Syrian rebels try to siege

The recent victories have shifted the momentum of the conflict in Assad's favor and given the Syrian leader greater leverage in proposed peace talks that the U.S. and Russia are trying to convene to end the civil war.

The intense fighting in the eastern Ghouta area began on Friday when several rebel groups attacked government forces, according to the British-based Syrian Observatory for Human Rights and an activist based in Qalamoun.

The activist spoke on condition of anonymity for fear of government reprisals.

There was no word on the battle from government media.