Angry protesters stormed the American embassy complex in Baghdad on Tuesday following US air attacks this week that killed 25 fighters from an Iran-backed Shia group in Iraq.

Stability is vital to Iraq’s position as Opec’s second-largest oil exporter. Persistent unrest is posing a threat to the activities of international oil companies (IOCs) that operate giant fields in the Basra region.

The US ambassador to Iraq and other staff had earlier been evacuated from their embassy in Baghdad for their safety, Iraqi officials said, as thousands of protesters and militia fighters outside the gate denounced the air strikes.

Shouting "Down, Down USA!" the protesters tried to push inside the embassy grounds on Tuesday, hurling water bottles and smashing security cameras outside.

The US military carried out the strikes on Sunday against the Iranian-backed Kataib Hezbollah, calling it retaliation for last week's killing of a US contractor in a rocket attack on an Iraqi military base that it blamed on the group.

The protesters raised flags of the powerful paramilitary group Hashd al-Shaabi (Popular Mobilisation Forces), of which Kataib Hezbollah is part, and several people climbed over the wall of the embassy and chanted "Death to America" and "No, No America", witnesses said.

The storming took place after mourners held funerals for fighters killed in a Baghdad neighbourhood, after which they marched on to the heavily fortified Green Zone and kept walking till they reached the embassy.

Ten demonstrators were wounded by security forces, according to a statement from the umbrella group to which the Kataib Hezbollah militia belongs. Protesters streamed into the compound after smashing down the guardpost gate with hammers, according to televised footage.