BAGHDAD — An Iraqi tribal leader says an airstrike has killed 19 pro-government tribal Sunni fighters south of the town of Mosul, which is held by the Islamic State group.

Sheikh Nazhan al-Lihaibi says the airstrike took place at 2 a.m. Wednesday, following hours of clashes between pro-government forces and IS militants in the Haj Ali area.

It was unclear who carried out the strike.

An officer at Iraq’s military operations command confirmed there was an airstrike in the area, but could not say if it was carried out by Iraq or the U.S.-led coalition. He spoke on condition of anonymity because he was not authorized to brief the media.

The U.S.-led coalition did not immediately respond to a request for comment.