Three Katyusha rockets have hit Baghdad International Airport, killing four people, according to the Iraqi military.

The missiles landed near the air cargo terminal, setting several cars on fire, early on Friday morning.

There was no immediate claim of responsibility for the attack.

Meanwhile the Iraqi Shia Popular Mobilization Forces (PMF) said in a post on Facebook that its director of public relations had been killed in what it described as “cowardly U.S. bombing.”

It comes a week after a US contractor was killed by a rocket attack on an Iraqi military base near Kirkuk.

Iraq protests: Death toll soars as live rounds and tear gasfire Show all 17 1 /17 Iraq protests: Death toll soars as live rounds and tear gasfire Iraq protests: Death toll soars as live rounds and tear gasfire Iraqi protesters take cover behind a barricade on Al-Jumhuriya Bridge during an anti-government demonstration in the Iraqi capital Baghdad on 25 October, 2019. AFP/Getty Iraq protests: Death toll soars as live rounds and tear gasfire Protesters push down concrete walls during a protest over corruption, lack of jobs, and poor services, in Baghdad. Reuters Iraq protests: Death toll soars as live rounds and tear gasfire Anti-government protesters try to break into the provincial council building during a demonstration in Basra. AP Iraq protests: Death toll soars as live rounds and tear gasfire Iraqi women protesters march with national flags during an anti-government demonstration in the central holy shrine city of Najaf. AFP/Getty Iraq protests: Death toll soars as live rounds and tear gasfire An Iraqi protester uses a mobile phone to take a selfie photo with an army soldier standing atop a humvee during a demonstration outside the local government headquarters in the southern city of Basra. AFP/Getty Iraq protests: Death toll soars as live rounds and tear gasfire Iraqi protesters gather during an anti-government demonstration at the burning local government headquarters in Nasiriyah, the capital of Iraq's southern province of Dhi Qar. AFP/Getty Iraq protests: Death toll soars as live rounds and tear gasfire Iraqi protesters wave a national flag as they stand atop the gatehouse to the local government headquarters in the southern city of Basra. AFP/Getty Iraq protests: Death toll soars as live rounds and tear gasfire An Iraqi protester throws back a tear gas canister fired by security forces amid clashes during an anti-government demonstration in Baghdad. AFP/Getty Iraq protests: Death toll soars as live rounds and tear gasfire Iraqi protesters carry away an injured protester following clashes during an anti-government demonstration in Baghdad. AFP/Getty Iraq protests: Death toll soars as live rounds and tear gasfire Iraqi security forces stand guard on Al-Jumhuriya Bridge during an anti-government demonstration in Baghdad. AFP/Getty Iraq protests: Death toll soars as live rounds and tear gasfire Anti-government protesters gather in Tahrir Square during a demonstration in central Baghdad. AP Iraq protests: Death toll soars as live rounds and tear gasfire The burning local government headquarters in Nasiriyah, the capital of Iraq's southern province of Dhi Qar. AFP/Getty Iraq protests: Death toll soars as live rounds and tear gasfire Protesters take cover behind a concrete barricade during a demonstration in Baghdad. AFP/Getty Iraq protests: Death toll soars as live rounds and tear gasfire Iraqi paramedics help injured protesters in Baghdad. AFP/Getty Iraq protests: Death toll soars as live rounds and tear gasfire Iraqi protesters gather in Baghdad. AFP/Getty Iraq protests: Death toll soars as live rounds and tear gasfire An Iraqi protester takes cover between concrete barricades in Baghdad. AFP/Getty Iraq protests: Death toll soars as live rounds and tear gasfire Protesters take cover from teargas canisters fired by security forces in Baghdad. AFP/Getty

The US claimed Kataib Hezbollah, an Iranian-backed Iraqi Shia militia, was responsible and carried out airstrikes on the group’s bases in retaliation.

Then on Tuesday the militia’s supporters stormed the US embassy compound in Baghdad and set it on fire.

The latest rocket attacks took place shortly after defence secretary Mark Esper issued a warning to “Iran and its proxy militias”.

“We will not accept continued attacks against our personnel and forces in the region,” he said in a statement.

“Attacks against us will be met with responses in the time, manner, and place of our choosing. We urge the Iranian regime to end their malign activities.”

Kataib Hezbollah is regarded by the US as a terrorist group despite being part of Iraq’s state-sponsored PMF.