NAJAF, March 29: Four US soldiers died on Saturday when a man driving a taxi set off a bomb at a US roadblock near Najaf, southern Iraq, making it the first suicide attack since the United States invaded Iraq.

The bombing followed a pattern in which Iraqi forces, mainly militiamen loyal to President Saddam Hussein, have dressed as civilians to launch attacks.

Baghdad said the suicide bomber was a military officer seeking to teach the Americans. Eleven US servicemen had been killed in the incident, a spokesman said. He warned of more such attacks.

The bombing occurred when a man in a taxi drove up alone to a checkpoint on a desert road north of Najaf and “beckoned” US soldiers over to him, US Army Colonel Will Grimsley said.

“As they (soldiers) approached, he detonated the bomb, killing himself and four soldiers,” Colonel Grimsley said. There were no other casualties, he added.

Iraqi state television later identified the bomber as a non-commissioned officer, Ali Jaafar Musa Hammadi al-Numani, who wanted to “teach the invaders a lesson in the same manner of our Palestinian martyrdom fighters” who have carried out suicide attacks against Israel.

“This is a blessed start. The enemies will face steadfastness, courage and martyrdom’s souls,” it warned, adding that the attack also left “two armoured personnel carriers destroyed and two tanks damaged”.

Describing the attack, the television said that “after kissing the holy Quran”, Numani “drove a booby-trapped car toward enemy tanks and armoured personnel at the outskirts of Najaf”.

“He turned himself, his car and the explosives that he was carrying into a destruction missile by exploding himself,” it said.

President Saddam Hussein decided to award the soldier two top posthumous medals of honour, including the decoration of Umm al Maarik, or the Mothers of All Battles, as Baghdad calls the 1991 war.

Iraqi Vice President Taha Yassin Ramadan later added: “This is only a beginning and you will hear good news in the coming days. We will use any means to stop the enemy and kill the enemy.

“The whole Iraqi people, including its women, will transform themselves into Fedayeen (martyrdom fighters),” he vowed at a press conference in Baghdad.

The four confirmed deaths brought to six the number of soldiers killed in the US Third Infantry Division since the invasion began on March 20. One soldier was killed by an Iraqi while another died in a road accident.

Colonel Grimsley also said later that US forces opened fire and “destroyed” three other standard Iraqi orange-and-white taxis that ran US roadblocks in the same area and within the same 30-minute period.

There was no evidence the other cars were laden with explosives because they did not blow up when armoured Bradley Fighting Vehicles blasted them with their heavy guns, the colonel said.

He did not say how many people died in the other taxis.

US forces, which must “strike a balance between helping Iraqi civilians and protecting” themselves, will now have to behave more strictly at checkpoints, he added.

US officials have been expressing growing frustration over how to fight an “enemy which hides among a civilian population” they want to win over or keep on their side.

Iraqi fighters switch from uniforms to civilian clothes at will while launching attacks from “sites that US forces are reluctant to hit for fear of harming civilians”, an official said.

Major John Altman, a US intelligence official, had warned before the suicide bombing occurred that US forces might face the Fedayeen paramilitary group’s “White Ninjas” male and female suicide bombers, as they march toward Baghdad.

ANOTHER ASSAULT:Meanwhile, US-led forces mounted one of their fiercest air assaults yet on Baghdad on Saturday, targeting the centre and outskirts of the city with repeated bombings that drew blasts of Iraqi anti-aircraft fire.