US soldiers Iraq
US soldiers training Iraq's 72nd Brigade in Basmaya base, south of Iraqi capital, BaghdadAhmad al-Rubaye/AFP/Getty Images

A US soldier has been killed during fighting against Islamic State (Isis) in northern Iraq, officials said. Defence Secretary Ash Carter said the serviceman died in combat near the city of Irbil, where American forces are assisting Kurdish troops battling IS (Daesh).

"It is a combat death," Carter told reporters in Stuttgart, Germany, where he is on an official trip. The identity of the soldier was not immediately released and neither was the branch of the military that the serviceman was serving with.

The US Central Command (CENTCOM) specified the soldier was killed by "enemy fire". "A coalition service member was killed in northern Iraq as a result of enemy fire," it said in a statement. "Further information will be released as appropriate."

A military official told AP the service member was hit while advising Peshmerga troops in the area, after IS militants broke into the Kurdish forward line. The slain soldier was about three miles from the frontline inside Kurdish territory when he was killed.

The death represents the third American fatality since Washington launched its aerial campaign to degrade the Islamist group. In March a rocket fired by IS killed staff sergeant Louis F Cardin, 27, in at a coalition outpost near the town of Makhmur.

Five months earlier, master sergeant Joshua Wheeler, 39, was killed during an overnight mission to rescue hostages, becoming the first American to die in combat in Iraq since 2011.