Syrian regime forces have attacked Aleppo with barrel bombs for a second day, with scores of people killed in 48 hours, according to the Syrian Observatory for Human Rights.

At least 36 people were killed in Sunday's attacks on Syria's second city, the London-based monitoring group said after reporting 85 deaths the previous day.

Regime forces targeted opposition-held districts in eastern Aleppo with barrel bombs - oil drums or cylinders packed with explosives and shrapnel.

Rami Abdel Rahman, the Syrian Observatory's director, told AFP news agency that 21 people were killed in three waves of attacks on the Tareq al-Bab district, including 13 children.

Another 15 died in separate air raids and barrel-bomb attacks on Aleppo.

Amateur videos posted online by opposition media activists showed scenes of panic from recent aerial bombardments.

In one video, a young man carries the limp body of a child through a wrecked residential neighborhood whose buildings are barely discernible through thick clouds of dust.

Dazed children shield their faces with their shirts as a man leads two women covered in soot away from the apparent site of the attack.

Barrel bombs have killed more than 700 people in Syria in the past six weeks.

Controversial weapon

The use of barrel bombs has been denounced as indiscriminate, not least by Western powers at last week's peace talks in Switzerland.

The first round of negotiations wound up on Friday in Geneva without progress towards ending Syria's three-year war or reducing the violence.

Western powers proposed a UN Security Council resolution in December to condemn the use of barrel bombs, which they say indiscriminately target civilians.

But Russia, a staunch ally of President Bashar al-Assad, has repeatedly blocked such plans in the Security Council.

Once Syria's economic hub, large parts of Aleppo have been devastated by the fighting that began there in mid-2012. The city is split into areas held by regime and opposition forces.

PHOTO CAPTION

In this citizen journalism image provided by Aleppo Media Center (AMC), an anti-Bashar Assad activist group, and authenticated based on its contents and other AP reporting, Syrian citizens fill water in a bucket to extinguish shops in flames caused by a Syrian government forces warplane attack, at al-Bab neighborhood in Aleppo, Syria, Saturday, Feb. 1, 2014.

Al-Jazeera