It said 40 Commando, one of the British units that took part in the US-led invasion of Iraq in March 2003, would spearhead reinforcements that will also include a unit of the elite Special Boat Service.

It added that the troops would be tasked with regaining control of the city of Najaf, south of Baghdad, where militia loyal to wanted Shiite cleric Moqtada Sadr have clashed with coalition forces.

"We have been asked for more men. The Royal Marines will be the lead element," the Sun quoted an unnamed senior government minister as saying.

"It's highly sensitive, but the announcement is due next week."

Besides the Royal Marines and Special Boat Service, the Sun said "several thousand" additional troops, thought to include elements of the Parachute Regiment, would be sent to British-occupied southern Iraq.

The Sun said the extra British troops would replace the 1,300 Spanish soldiers who are being pulled out of Iraq following the election of a new Socialist government in Madrid two months ago.

The Spanish pullout is due to be completed by May 27.

A Ministry of Defence spokesman in London, contacted by AFP, refused to confirm the Sun report, saying only that troops numbers in Iraq were constantly being reviewed with coalition partners.

"No decisions have been taken," the spokesman added.

WAR.WIRE