Iraqi Vice-President Taha Yassin Ramadan has warned that suicide attacks against the invaders would become a "routine military policy", following an attack against American soldiers on Saturday.

Ramadan said an army officer -- Ali Jaafar al-Noamani -- had carried out the "martyrdom operation" in the central Iraqi town of Najaf, which killed four US soldiers.

The attacker, dressed in civilian clothes, drove a taxi to a checkpoint being operated by the US Army's 1st Brigade, 3rd Infantry Division, and, as the soldiers approached it, detonated the bomb.

"This is just the beginning. You will hear more pleasant news later," Ramadan said at a press conference.

Iraqi television said President Saddam Hussein had awarded two posthumous medals to the suicide bomber.

At the US Central Command, Major General Victor Renuart said: "These kind of actions are symbolic of an organisation that is getting a little bit desperate."

Meanwhile, the coalition forces are marching towards Baghdad. The area surrounding Najaf, 120km south of the capital on the Euphrates River, has been the scene of intense fighting.

At least 300 Iraqi soldiers have died in a battle for a river bridge, CNN said adding coalition forces are now control of the crossing.

CNN quoted British and US officials as saying that they are taking steps to eliminate the paramilitary threat.

US bombers are also believed to be targeting units of the Republican Guard defending the capital.

Down south, US aircraft destroyed a two-story building in Basra, where around 200 Iraqis were meeting on Friday, the US Central Command said on Saturday.