A resident searches through rubble at a site hit by what activists said was a barrel bomb dropped by forces loyal to Syria's President Bashar al-Assad in the Tariq al-Bab neighbourhood of Aleppo. Picture: Hosam Katan

Aleppo - At least 246 people, including 73 children, have been killed in five days of Syrian army barrel bombing of rebel-held held areas of second city Aleppo, an NGO said on Thursday.

Hundreds more have been wounded in the raids using the controversial unguided munitions, condemned by rights groups as indiscriminate, the Syrian Observatory for Human Rights said.

The heavy casualty toll has sparked a mass exodus from the worst-hit neighbourhoods in the east of the city, the Britain-based monitoring group added.

The latest series of barrel bomb attacks began on Saturday, with at least 85 people killed in a single day of raids in the eastern part of the city.

Once the country's economic hub, Aleppo has been divided between government control in the west and rebel control in the east since a rebel offensive in mid-2012.

The latest raids have accompanied a government ground assault on the eastern outskirts of the city, aimed at building on the army's recent recapture of areas outside Aleppo city.

The gains allowed the reopening the Aleppo international airport, after its closure for more than a year.

And security sources have told Syrian media that troops plan to take three neighbourhoods in east Aleppo and three more in the north in a bid to retake the rebel-held sector of the city in a pincer movement.

The attacks have prompted thousands of civilians to flee, some across the border to Turkey.

Persistent fighting between the jihadist Islamic State of Iraq and the Levant and other rebel groups has left much of Aleppo province unsafe, forcing some fleeing civilians to seek refuge in government-held areas of the city, the Observatory said. - AFP