At least 13 people were killed across Syria on Saturday as fierce fighting raged in Aleppo and Damascus, the country’s two biggest cities, a rights group said.

Overnight in Aleppo, rebel forces withdrew from the district of Izaa where the state television building is situated, according to the Syrian Observatory for Human Rights.

“Rebel forces planted explosives there, and regime forces shelled the area,” the Britain-based Observatory reported. “The rebels then withdrew from the area.”

The fighting broke out when rebel fighters tried to storm the building, Observatory director Rami Abdel Rahman said.

According to state news agency SANA, “mercenary terrorist groups attacked civilians and the state TV building (in Aleppo), while the army defended it.”

Clashes also raged on Saturday in the districts of Salaheddin and Saif Al Dawla, the Observatory added.

“Helicopters and fighter jets were seen overhead in Aleppo,” the watchdog added.

In Damascus, violent clashes broke out in the southern Tadamun neighbourhood, scene of fighting a fortnight ago.

The army also shelled the neighbourhood on Saturday morning, in what the Observatory described as “the most violent that the district has seen.”

Violence also broke out in the Jobar area of the capital, the monitoring group said, adding that violence had killed at least six people in Damascus province on Saturday.

Elsewhere, another seven people were killed, six of them in eastern Deir Ezzor and one in the coastal province of Latakia.