The Pentagon said it is investigating reports that an air strike in Iraq killed at least 19 pro-government Sunni fighters south of Mosul, where government forces are massing for an effort to retake the city from the extremist group Islamic State (IS).
Sheikh Nazhan al-Lihaibi said the strike occurred early on October 5, following hours of clashes between his troops and IS militants in the Haj Ali area. He said five more fighters were wounded.
The U.S.-led coalition said it had carried out strikes in the area at the request of Iraqi security forces and destroyed a building, killing eight enemy fighters.
"We are aware of the reports that Sunni tribal fighters were in the building that was struck and we are taking those reports seriously," a coalition spokesman said, adding the incident is under investigation.
Mahmoud Ali, an officer with Lahaibi's tribal militia, said that U.S. special forces troops arrived in the area, warning them of a future strike and telling them to keep away. It was unclear if the tribal fighters acted on this advice.
Based on reporting by AP and AFP