"Two fixed-wing drones rigged with explosives were engaged and destroyed by defensive capabilities at the Iraqi Al-Asad Air Base early this morning," the official said.

"The attempted attack was unsuccessful. All forces are accounted for."

It is the second such attack in 24 hours targeting the coalition in Iraq. On Monday, the coalition shot down two armed drones targeting its compound at Baghdad airport.

The attacks come as Tehran and its allies across the Middle East held emotional commemorations marking the second anniversary on Monday of the assassination of Iranian commander General Qassem Soleimani and his Iraqi lieutenant in a US drone strike at Baghdad airport.

Coalition troops switched to a training and advisory role with the end of their combat mission early last month.

"While we have ended our combat mission, we maintain the inherent right of self-defence," the official said.

"These are attacks against Iraqi installations, and an attack against the Iraqi people and the military that protects them. We maintain a minimal footprint on Iraqi bases -- the coalition no longer has its own bases in Iraq."