The embassy said in a statement there were "no reported casualties" in the attack Tuesday which it said "was initiated by Iran-aligned militia groups which operate freely in Iraq".

It called on Iraq to protect its personnel and facilities.

The compound, located within the airport perimeter but attached to the US embassy, provides logistical support and medical services, among other things.

The attack occurred amid rising regional tensions over the Gaza war and shortly ahead of a visit by Iranian President Masoud Pezeshkian to Iraq.

In its statement, the US embassy said Iraq had "repeatedly committed to protect diplomatic missions" and US military personnel in the country "at the government of Iraq's invitation".

"We again call on the government of Iraq, as we have done on many occasions, to protect diplomatic and coalition partner personnel and facilities", it added.

"We reiterate that we reserve the right to self-defence and to protect our personnel anywhere in the world."

A senior military official, speaking on condition of anonymity, told AFP on Wednesday that "two Katyusha-type rockets" had caused the explosion.

US military and civilian facilities in Iraq have come under repeated attack, both by Sunni Muslim extremists and by Shiite armed groups backed by Iran.