A US service member died of wounds sustained from an explosion outside the northern Iraqi city of Mosul on Saturday, the US-led military coalition said.

A statement from the department of defence said first lieutenant Weston Lee, 25, of Bluffton, Georgia, died on 29 April from injuries while conducting security. He was in Mosul as part of Operation Inherent Resolve.

The incident is under investigation, the department said.

US-backed forces have been fighting to retake the Islamic State stronghold of Mosul.

News of the casualty came as Donald Trump marked his first 100 days in office. In last year’s presidential election campaign, Trump vowed to give priority to destroying Isis, which operates mostly in Syria and Iraq.

The news follows the deaths of two US soldiers in a raid in Afghanistan this week. The men, both army rangers, were identified as Sgt Joshua Rodgers, 22, and Sgt Cameron Thomas, 23. A third soldier was wounded.