The death toll from an air strike by US-led forces on the northern Syrian province of Aleppo has risen to 52 including seven children, a group monitoring the conflict said on Saturday.

Rami Abdulrahman, who runs the British-based Observatory for Human Rights, said the death toll from Friday’s strike was the highest civilian loss in a single attack by US and Arab forces since they started air raids against hardline Islamist militant groups in Syria such as Islamic State. US-led forces are also targeting the group in Iraq.

Major Curtis Kellogg, a spokesman for US Central Command, told the Associated Press there was no information to corroborate the Observatory’s claims. However, Kellogg said: “We take all allegations seriously and will look into them further.”