Syrian military helicopters dropped more improvised "barrel bombs" on the northern city of Aleppo on Sunday, a monitoring group said, bringing the death toll to at least 83 people in the latest episode of a campaign that many consider a war crime, Reuters reported.
Most of the victims killed since Friday have been civilians from the city's eastern districts, including women and children, according to the British-based Syrian Observatory for Human Rights, which has a broad network of sources across Syria.
The use of barrel bombs - oil drums or cylinders packed with explosives and shrapnel - has drawn international condemnation, not least from Western powers at last week's peace talks in Switzerland.
The first round of negotiations wound up on Friday without progress towards ending Syria's three-year civil war or reducing the violence, which regularly kills more than 100 people a day.
Western powers proposed a U.N. Security Council resolution in December to condemn the use of barrel bombs, which they say indiscriminately target civilians. The weapons have killed well over 700 people in Syria in the past six weeks.
But Russia, a staunch ally of President Bashar al-Assad, has repeatedly blocked such plans in the Security Council.
Syrian authorities say they are targeting the rebels who control large portions of Aleppo, Syria's largest city and once its business hub.
Amateur videos posted online by opposition media activists showed scenes of panic from recent aerial bombardments.