It said that figure might rise further as rescue and search operations continued, adding that children were also among at least 30 people wounded in the attack.

Al-Bab falls within the areas of Aleppo province held by rebels. Other parts are held by Syrian government troops.

The US-backed Syrian Democratic Forces (SDF), spearheaded by Kurdish groups who have opened a dialogue with the Damascus-based government, also control parts of the north and northeast. The head of the SDF's media centre, Farhad Shami, said the group had nothing to do with Friday's attack.