BAGHDAD: A drone packed with explosives hit an Iraqi base housing US troops early Saturday causing damage but no casualties, the Iraqi military and the US-led coalition said.

The attack on the Ain Al-Asad air base was the fourth targeting US troops in Iraq in less than a week, as an armed campaign blamed on pro-Iranian groups intensifies. "Each attack... undermines the authority of Iraqi institutions, the rule of law and Iraqi national sovereignty," said coalition spokesman Colonel Wayne Marotto.

"No injuries reported. A hangar was damaged," he said in a tweet.

It was only the second time authorities publicly confirmed a drone had been used in an attack on a target inside Iraq.