Fighting raged across the country as international mediator Lakhdar Brahimi sought a political solution to Syria's civil war, meeting senior U.S. and Russian officials in Geneva.
But the two world powers are still deadlocked over Assad's fate in any transition.
The United States, which backs the 21-month-old revolt, says Assad can play no future role, while Syria's main arms supplier Russia said before the talks that his exit should not be a precondition for negotiations.
Syria is mired in bloodshed that has cost more than 60,000 lives and displaced millions of people. Severe winter weather is compounding their misery.