Syrian activists say government airstrikes have killed at least eight people in a northern town held by the Islamic State.

The Britain-based Syrian Observatory for Human Rights said the airstrikes targeted the city of al-Bab on Thursday. The Observatory, which obtains its information from a network of activists on the ground, said the dead included women and children and that the toll was likely to rise because many people were wounded.

The Aleppo Media Center, a local activist group, said 15 people were killed in four airstrikes that targeted a crowded sheep market. Conflicting death tolls are common after such strikes.

Human rights groups and local activists say Syrian government forces often show disregard for civilians when targeting suspected militants.