Syrian activists say many civilians have been killed when suspected government helicopters dropped barrel bombs on a wake held for children who died in earlier airstrikes in rebel-held Aleppo.

Hospital officials in Aleppo say the death toll from the two barrel bombs dropped Saturday, 27 August in the Bab al-Nairab neighborhood is likely to rise, according to an AP report.

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Helicopters reportedly dropped the barrel bombs in the assault, which killed 15 members of the same family, Nagib al-Ansarit told Andalou news agency.

The local Shabha Press news agency gave a higher number of casualties, saying that 23 people were killed in Saturday's attack. The strikes on Saturday were blamed on militia loyal to the regime of President Bashar al Assad, according to Deutsche Welle.

The Syrian Observatory for Human Rights said the air offensive hit Aleppo, near a tent where relatives of people killed in a barrel bombing earlier this week were receiving condolences.

"There was a first barrel bomb and when people gathered and the ambulances arrived, a second barrel struck and there were more deaths," said an AFP reporter.

"One ambulance was completely destroyed," he added, citing the local civil defence unit.

Mohammed Khandakani, a volunteer at the hospital, said one of the wounded told him a barrel bomb was dropped as people paid their condolences for children killed in an airstrike on Thursday, 25 August that left 11 children dead. Minutes later, another barrel bomb was dropped, said Khandakani, which left an ambulance driver injured, and slowed down the search and rescue efforts.

"Fifteen civilians, among them 11 children, were killed in a barrel bomb attack on the Bab al-Nayrab neighbourhood" in the south of Aleppo city, said the Syrian Observatory for Human Rights monitor. The victims reportedly included a three-year-old girl and a two-month-old baby.

Video shared by activists show two boys covered in dust crying and hugging each other as they learn that another of their siblings had been killed in Thursday's attack. "My brother is gone," one sobbed, according to CNN.

Amnesty International says the use barrel bombs is a common tactic of the Syrian regime, although President Bashar Al-Assad has repeatedly denied using the weapons.

The strikes came amid Russia's agreement to a 48-hour ceasefire. Residents from the city of Daraya left on buses on Friday, 26 August as part of an evacuation agreement between the Syrian government and rebels in the war-battered country.

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