The attack on Sunday hit a position near the border town of Al-Qaim held by Brigade 45, a unit belonging to the powerful Hashed al-Shaabi paramilitary force.

"An investigation is ongoing now to determine what happened with the strike," Iraq's military spokesman Yehya Rasool told AFP.

The Hashed had been quick to blame Israel on Sunday, saying Israeli drones targeted the position with US air cover.

"As part of the string of Zionist attacks on Iraq, the evil Israeli crows have returned to target the Hashed al-Shaabi, this time with two drones inside Iraqi territory," the statement said.

The attack killed Kazem Mohsen, Brigade 45's "logistical support chief" and a member of its rocket squad, also known by his nom de guerre Abu Ali al-Dabi.

Hundreds mourned at a funeral procession for him in Baghdad on Monday morning, including Ahmad al-Assadi, a member of parliament and spokesman for the Hashed's parliamentary bloc "Fatah".

"We will work in the coming days to hold an emergency parliamentary meeting to discuss this issue and take the appropriate decisions," he said in a video published by the Hashed.

The attack was the latest in a string of blasts and drone sightings at Hashed bases across Iraq, for which no one has claimed responsibility.

The Iraqi government has carried out investigations into some of those incidents, blaming an unidentified drone for at least one and saying another was a "premeditated" act without making specific accusations.