The US military has announced that the entire crew of six was killed when an aerial refuelling aircraft crashed in Iraq — an incident it said was not caused by “hostile fire”, AFP reports.

“All six crew members aboard a US KC-135 refuelling aircraft that went down in western Iraq are now confirmed deceased,” US Central Command (Centcom) says in a social media post.

“The circumstances of the incident are under investigation. However, the loss of the aircraft was not due to hostile fire or friendly fire,” Centcom, which is responsible for US forces in the Middle East, adds.

This brings the total of confirmed US deaths in the operation against Iran to 13.