Syrian aerial bombardment on a residential area and a crowded market in a town in northern Aleppo province has reportedly killed dozens of people, including women and children.
Saturday’s attack on al-Bab, which saw helicopters belonging to President Bashar al-Assad's forces drop explosives-filled barrels, killed at least at 28 people, according to Syrian Observatory of Human Rights.
The UK-based group said three children were among the dead.
The Local Coordination Committees activist group, meanwhile, said 29 people were killed. Scores of others were injured.
Al-Bab, 30km northeast of the city of Aleppo, is held by the Islamic State of Iraq and the Levant (ISIL) group and is a frequent target of Syrian military strikes that often kill civilians.
On May 31, government air strikes that hit a packed market in al-Bab killed at least 55 people, most of them civilians.
A US-led coalition is waging a separate air campaign against ISIL in Syria, but rejects the idea of partnering with Assad, who it sees as an obstacle to peace in Syria.
The US and its allies carried out 34 air strikes against ISIL targets in Syria and Iraq on Friday, the US military said.
Various ISIL targets near the city of Hasaka were hit in 12 of the 17 strikes in Syria, a military statement said on Saturday.
The allied forces also carried out 17 air strikes near eight cities in Iraq, including four near the northern city of Mosul, it said.