"Twelve Kurdish citizens, including six children... were killed in government shelling of an area in the town of Tal-Aran," said the Syrian Observatory for Human Rights, adding at least 11 other people were wounded.

The town is east of Aleppo city, and near the town of Sfeireh, which is largely controlled by jihadist fighters and has been a key target for the regime in recent weeks.

The Observatory said another nine people had been killed in shelling on Tal-Aran and the surrounding area on Thursday, including five children, bringing the toll in 24 hours to 21 people.

Tal-Aran is considered strategic because of its location on the main road between Aleppo city and Sfeireh, which is near a regime military site that is believed to hold some of Syria's chemical arms.

In eastern Syria, meanwhile, rebels advanced in the city of Deir Ezzor after fierce clashes with regime troops overnight.

"Clashes took place overnight between rebels and regime forces in several neighbourhoods in the city of Deir Ezzor," said the Observatory.

The Britain-based group also reported regime air strikes and clashes in the city of Deir Ezzor, which lies in the eastern province of the same name, on Friday morning.

The strikes left people wounded and destroyed several houses.

The Observatory, which relies on a network of activists, doctors and lawyers on the ground, said initial reports suggested rebels had taken an area near the Rashdiya district that had been under government control.

"Fighters from the Al-Nusra Front executed 10 soldiers from the regime forces after they captured them following clashes in Rashdiya," it said.

On Thursday, state television said a senior military intelligence officer was killed in Deir Ezzor city.

"Major General Jamaa Jamaa was martyred while carrying out his national duties to defend Syria and its people and pursuing terrorists in Deir Ezzor," state television said.

The Observatory said he was killed by a sniper in clashes between jihadist opposition fighters and regime troops in Rashdiya.

Jamaa was a leading intelligence official in Syria and one of Damascus's top security officers in Lebanon during Syria's military deployment in the country between 1976 and 2005.