At least 16 people were killed on Saturday when unidentified helicopters dropped barrels packed with explosives on a gathering of mourners in the divided city of Aleppo in northern Syria, a monitoring group reported.
The explosives, known as barrel bombs, were dropped on the rebel-held neighbourhood of Bab al-Neirab on the outskirts of Aleppo, the Syrian Observatory for Human Rights added.
The victims were mourning 15 people, including 11 children, who had been killed in an air attack two days earlier in the same district.
Aleppo, Syria's pre-war commercial hub, has been divided between forces of Syrian President Bashar al-Assad in the west and rebels to the east since fighting erupted for the control of the city in mid-2012.
In July, a government offensive saw eastern Aleppo lose its last link with the rebel-held hinterland, threatening the survival of the last major urban centre to remain in the hands of the opposition.
But earlier this month, rebels including jihadist insurgents broke through government lines in southern Aleppo and linked up with fighters inside the eastern rebel side of the city.