"The temporary withdrawal of employees has nothing to do with security in southern Iraqi oil fields or any threats," Oil Minister Thamer al-Ghadban said.

"The reasons are political and probably linked to tensions in the region," he added in a statement released by the oil ministry.

Ghadban called the move to pull out staff from the West Qorna oil field west of the southern port city of Basra "unacceptable and unjustified".

Exxon did not confirm the withdrawal.

"We are closely monitoring. As a matter of practice, we don't share specifics related to operational staffing at our facilities," a spokeswoman said.

"ExxonMobil has programmes and measures in place to provide security to protect its people, operations and facilities. We are committed to ensuring the safety of our employees and contractors at all of our facilities around the world," she added.

On Wednesday the United States ordered the evacuation of non-emergency staff from its Baghdad embassy and Arbil consulate, citing an "imminent" threat from Iranian-linked armed groups in Iraq.

It came 10 days after the Pentagon deployed an aircraft carrier task force and B-52 bombers to the Gulf to fend off an unspecified alleged plot by Tehran to attack US forces or allies.

Both the US and Iran are key allies of Shiite-majority Iraq, and Baghdad has been under pressure from Washington to limit ties with its Shiite-ruled neighbour.

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