The US army's elite division was locked in a fierce house-to-house battle with about 500 members of Iraq's feared Fedayeen militia for control of the holy Shiite city, 80 kilometres (50 miles) southwest of Baghdad, he added.

The dead soldier was killed soon after the battle began on Saturday, Swart said, but was unable to say how many, if any, Iraqi soldiers and civilians had been killed in the two-day battle.

A batallion of infantrymen from the 101st, backed by Apache and Kiowa Warrior attack helicopters, was involved in the fighting, but the forces were having trouble combatting the urban warfare tactics of the approximately 500 Fedayeen soldiers, he added.

"They are in the city now and they are trying to clear out the Fedayeen death squads," Swart said. "They are going door-to-door... it is high intensity urban conflict."

Swart said the Fedayeen were seeking refuge in houses and other buildings where there were civilians.

"The Fedayeen have been hiding pretty much anywhere they can, they don't care who they might endanger."

Further highlighting the dangers for US troops, Swart said one Bradley fighting vehicle had been destroyed by an Iraqi rocket propelled grenade in the city, although nobody was injured in the incident.

The fighting in Karbala mirrors the battle for Najaf, another important city for Iraq's majority Shiite population about 50 kilometres further south.

Military officials have said the 101st secured Najaf after nearly a week of intense fighting, during which forces loyal to Iraqi President Saddam Hussein reportedly sought refuge near the Tomb of Ali, one of the Shiites' most sacred mosques.

Swart said Najaf was still under the control of the US military and humanitarian shipments would start soon.

However there are still pockets of resistance in Najaf, with five soldiers injured in a night-time ambush in the city on Saturday, Swart said without going into further details.

The 101st has been given the task of securing Najaf, Karbala and other cities that the 3rd Infantry Division went through or bypassed in their lightning push on Baghdad, and is expected to edge closer to the capital over the next week.

The other major operation for the 101st involves a batallion of infantrymen working to clear tunnels and buildings at the Saddam International Airport, Swart said.

The 3rd Bigade's 3rd batallion reached Baghdad on Friday, shortly after the 3rd Infantry Division, and were carrying out their mission without major incident, Swart added.

"I haven't heard of any killed or wounded from them so I guess it's going pretty well," he said.

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