An Iraqi police officer instructs a bulldozer while Iraqi security forces remove cement blocks and opened the streets that were closed for security concerns around the Green Zone in Baghdad. Picture: Nasser Nasser/AP

Washington - The State Department is telling US citizens to leave Iraq as soon as possible.

"Due to heightened tensions in Iraq and the region, we urge US citizens to depart Iraq immediately," it says in a security alert, following a US strike that killed a top Iranian general in Baghdad.

A burning vehicle at the Baghdad International Airport following an airstrike in Baghdad, Iraq. The Pentagon said Thursday that the US military has killed General Qassem Soleimani, the head of Iran's elite Quds Force, at the direction of President Donald Trump. Picture: Iraqi Prime Minister Press Office via AP

"US citizens should depart via airline while possible, and failing that, to other countries via land."

Consular operations at the US embassy in Baghdad were suspended earlier this week following attacks on the building by supporters of an Iranian-backed militia.

Black smoke coming out of the US Embassy compound in Baghdad. Iran-backed militiamen withdrew from the embassy compound in Baghdad on Wednesday after two days of clashes with American security forces, but US-Iran tensions remain high and could spill over into further violence. Picture: Satellite image ©2020 Maxar Technologies via AP