Syrian opposition activists are reporting that a car bomb in a northern town held by Turkey-backed fighters has killed at least 13, and wounded dozens of people.

The Britain-based Syrian Observatory for Human Rights said at least 14 people were killed, and dozens wounded in the Sunday night blast in the center of the town, Azaz.

The Azaz Media Center, a local activist collective, said the blast killed at least 13 people and wounded many others.

The blast occurred after the "iftar" meal that breaks a daylong fast during the Muslim holy month of Ramadan.

The town, which was once controlled by rival Kurdish fighters opposed to Turkey, has been hit by similar attacks in the past.