Fierce clashes persisted overnight in Syria's commercial capital of Aleppo, stretching into a fourth day, Syrian authorities and opposition activists said.
The state news agency said today that regime forces fought with rebels in the Salaheddine and Sukkari neighbourhoods and claimed they inflicted heavy losses.
The Britain-based Syria Observatory, meanwhile, reported heavy fighting after midnight in several neighbourhoods as well as shelling by regime forces. Some areas also saw early-morning protests calling for the fall of the government.
Fighting broke out in Aleppo, Syria's largest city, over the weekend with rebels announcing a plan to liberate the city.
The operation comes as government forces appear to have reasserted control over the capital, Damascus, after a week of fighting.