Security sources told AFP that nine rockets hit the sprawling Ain al-Asad airbase, the largest of the Iraqi military compounds where foreign troops are based.

The attack came in three waves just after midnight, the sources said.

For the first time, Iran claimed responsibility for the attack, with state TV saying it had launched missiles on the base.

US installations across Iraq had faced some 15 rocket attacks in recent months but none were claimed.

US President Donald Trump was "monitoring the situation closely and consulting with his national security team," according to the White House.

The attack came after pro-Tehran factions in Iraq had vowed to join forces to "respond" to a deadly American drone strike last week outside the Baghdad airport.

The raid killed Iranian general Qasem Soleimani, seen as the "godfather" of Tehran's proxy network across the region, and Iraqi top commander Abu Mahdi al-Muhandis, the deputy head of Iraq's Hashed al-Shaabi military network.