Latest bomb takes US troop deaths to 500

Mounting casualties and greater guerrilla firepower sow doubts over schedule for handover and American withdrawal

The number of American troops killed in Iraq reached 500 yesterday after a large road-side bomb destroyed an armoured vehicle, killing three US soldiers and two Iraqi civil defence troops.

The explosion, at Taji, 20 miles north of Baghdad, flipped over a Bradley Fighting Vehicle, which then caught fire, indicating that guerrillas have started to use bigger bombs than in the past. A further two US soldiers were wounded, according to Lt Bill McDonald, spokesman for the 4th Infantry Division.

The guerrillas, mostly concentrated north and west of Baghdad in Sunni Muslim areas, have relied heavily on bombs planted in or beside the road to inflict casualties on US patrols and convoys. They have also used mortars to bombard American bases. Attacks by gunmen using sub-machine guns and rocket-propelled grenade launchers have proved less effective.

The attack at Taji brings to 500 the number of American troops killed either by enemy fire or in accidents since the war to overthrow Saddam Hussein began on 20 March last year. The number wounded over the same period is 2,895. Only 138 died and 550 were injured in the war up to 1 May, when President George Bush declared major combat over. The worst month so far was November, when 81 US soldiers were killed, although almost half of the deaths were caused when three helicopters were shot down in different parts of the country. Some 40 soldiers were killed in December and 22 so far in January.

The US military command, conscious of the political impact of casualties in the US, has sought to limit its losses by giving greater protection to its bases, limiting the number of patrols and relying more on Iraqi police, the civil defence corps and the fledgling Iraqi army.

This dependence will increase following news that the Americans will reduce troop strength in Iraq by about 20 per cent over the next few months. In the biggest rotation since the Second World War, most of the 130,000 American troops in Iraq will leave, to be replaced by a less heavily armed force of about 105,000.

Military officials insist, however, that although the new forces will have fewer soldiers, helicopters and tanks and less artillery, they should be more mobile and better suited to deal with guerrillas. Instead of the heavy equipment needed in the invasion of Iraq, the troops will have 323 new high-tech fighting vehicles known as Strykers, reinforced armoured Humvees and infantry armoured personnel carriers to counter the hit-and-run attacks and road-side bombings which cause most of the casualties.

"[It] will be a reduction in numbers, but we don't see it as a reduction in capability," a senior military official said in Baghdad.

Meanwhile, the US military has started a criminal investigation into the abuse of prisoners at a coalition detention centre in Iraq. The statement did not say what type of abuse was under investigation, but Iraqis say they often suffer the worst ill-treatment immediately after being picked up and before they reach a detention centre.

Mustafa al-Hussein, 17, a secondary school student from Fallujah, told The Independent on Sunday he had been arrested at his aunt's house with four other men. Plastic bags were put over their heads, and they were taken to a US base at a farm once belonging to Uday, a son of Saddam, outside Fallujah.

There, he said, "they took the bags off and caught us by our hair and smashed our faces into a wall in front of which we were standing. Later they made me drink a bottle and a half of water and then punched me in the stomach so I was sick." On the eighth day of detention Mr Hussein and three of the other men were released.