Rebel fighters wounded or killed in Aleppo
The BBC's Ian Pannell, in Aleppo, has seen skirmishes, with a number of rebel fighters wounded or killed.
Rebels with the Free Syrian Army (FSA) say they have repelled an army incursion and destroyed tanks, but there is no independent verification.
Western nations have warned of a potential massacre in Aleppo, Syria's most populous city, the BBC reports.
Early on Saturday morning, activists said Syrian tanks began moving in on south-western districts of the city.