Fri Jun 4, 2:40 PM ET


BAGHDAD (AFP) - The death toll of US troops killed in action in Iraq (news - web sites) exceeded 600 as five US soldiers were killed in an attack on their convoy on the edge of Baghdad's radical Shiite bastion of Sadr City.

The attack, which witnesses said involved a rocket-propelled grenade and a bomb, was launched on the convoy just hours after clashes broke out between troops and militiamen in the same neighbourhood.

"Four soldiers were killed and five wounded in an explosion on their convoy in Baghdad at around 1:10 pm (0910 GMT)," a military spokesman told AFP, adding that the nature of the device used was under investigation.

That brought the number of US soldiers killed in action in Iraq to 600 but the military announced later that a fifth soldier had died in the attack.

Witnesses had told AFP on the scene earlier that several soldiers had probably been killed in the attack against the vehicles on a highway running along the edge of the densely-populated slum.

According to the US military, 601 of its soldiers have now been killed in action since the invasion of Iraq in March 2003. Of those, 490 have died in action after US President George W. Bush (news - web sites) declared major combat in Iraq over on May 1.

"Every single one of these is sad. Every single one is unnecessary," a coalition military spokesman said.

"There is a growing determination that no death or injury is going to deter us from completing the mission," he added.

Witnesses said attackers fired a rocket-propelled grenade at one of the first vehicles and the convoy was rocked by a roadside bomb after it ground to a halt -- a now familiar pattern of attack on US patrols.

A burnt-out Humvee smouldered, letting off plumes of black smoke as military medics tended wounded soldiers and at least two military ambulances could be seen.

The army closed off the area while troops backed by tanks fired down side-streets to prevent jubilant groups of local youngsters from approaching.

Other witnesses said a television cameraman was wounded in the leg when soldiers fired warning shots to ward off a crowd.

The mayhem was a replay of earlier scenes in Iraq as angry crowds celebrated the blood of US soldiers spilled and jittery soldiers fired in the air.

At least one local resident who lives no more than 20 yards (metres) from the site of the bomb attack was seriously wounded by the explosion, his father Abdullah Zeidan said, his jalabiya stained with his son's blood.

That too was a sad commentary on the last year as insurgents' attacks on US soldiers have killed scores of Iraqi civilians.

At least 10,000 Iraqis are thought to have died since the US military invaded Iraq in March 2003 to oust Saddam Hussein (news - web sites).

In Sadr City, a district of around two million people that is home to supporters of Shiite fundamentalist cleric Moqtada Sadr, US troops have found themselves up against a different enemy to the one it has faced for most of the year-long occupation.

The coalition has mainly battled an unholy alliance of a rag-tag resistance from the Sunni Muslim community who ruled the country until the fall of Saddam and foreign fighters, but they now face violence from the Shiite majority.

Since April, the military has suppressed an uprising by Sadr who commands a wide following among the country's Shiite urban poor, complicating America's definition of the enemy in the post-Saddam landscape.

US officials expect more soldiers will lose their lives as they see no immediate end to the bloodshed, even with the planned handover of sovereignty to Iraq's new government on June 30.