Clashes also broke out between troops and rebel fighters in the Sukkari, Hamdaniyeh and Ansari districts of the northern city, scene of heavy fighting since July 20, the Syrian Observatory for Human Rights said, adding that at least 13 people were killed across Syria on Sunday.

Among those killed were at least two rebel fighters who died in Aleppo Sunday morning, the Britain-based watchdog said.

In Damascus, regime forces raided the district of Qaboon on Sunday, arresting several civilians, the Observatory said, adding that one of the detainees was a 12-year-old child.

After clashes with the rebels in the Rukn al-Din district on Saturday, the army set up new checkpoints there and in several other neighbourhoods of the capital.

In Damascus province, clashes broke out in Kfar Batna as regime forces shelled that village. The army also shelled Harasta, in the same province.

Elsewhere, regime forces pounded rebel-held Rastan in the central province of Homs, the Observatory said. "Regime forces dropped more than 60 shells on Rastan, at a rate of four to five shells a minute," the watchdog added.

On Saturday, violence nationwide killed 205 people -- 115 civilians, 38 rebel fighters and 52 soldiers, the Observatory said.

It is impossible to independently verify death tolls out of Syria, while the United Nations has stopped giving its own count.