Four U.S. soldiers with the 3rd Infantry Division were killed Saturday morning when a suicide bomber in a taxi attacked a military checkpoint in the central Iraqi town of Najaf, a U.S. Central Command spokesman said. 

The suicide bombing was the first against U.S. and British forces since the invasion of Iraq began. 

Coalition forces are viewing the suicide bombing as a warning sign. U.S. Central Command Director of Operations Maj. Gen. Victor Renuart Jr. condemned Saturday's attack as a terrorist act but said it did not change the coalition's strategy. 

"That kind of activity I think is something of a symbol of an organization that is getting a bit desperate," Renuart said. "Having said that, our troops do in fact train to those kinds of events." 

Iraq TV announced Sunday that President Saddam Hussein would give the family of the man who carried out Saturday's attack 100 million dinars, or about $35,000. 

Col. Will Grimsley, commander of the division's 1st Brigade, said an Iraqi in a taxi drove up to the checkpoint -- where soldiers try to determine civilians from Iraqi fighters in civilian clothes -- early Saturday morning. A sign in Arabic announces the roadblock, he said. 

The taxi driver reportedly gestured to the soldiers that his car was having mechanical problems. As the soldiers approached the vehicle, the driver detonated the bomb, killing himself and four soldiers, Grimsley said. 

The attack in Najaf and an earlier incident Saturday near Basra appeared to validate Iraqi Vice President Taha Yassin Ramadan's two-month-old threat of suicide bombings. 

Two Iraqis in civilian clothes near Basra flagged down a U.S. Army Humvee and told the soldiers inside they were members of the Saddam Fedayeen paramilitary group and were ordered to conduct suicide bombings against U.S. and British troops. 

The Iraqis told the Americans they had taken off their uniforms and wanted to surrender because they did not want to die for Saddam Hussein, reported a CNN correspondent who saw the incident. 

Ramadan first threatened the use of suicide attacks in Iraq and elsewhere in an interview with Germany's Der Spiegel in early February. He repeated that at a news conference Saturday in Baghdad. 

Ramadan: 'More good news in the coming days'
"This is only the beginning, and you will hear more good news in the coming days," Ramadan said Saturday. "These bastards will be welcomed at the level and in the way they deserve." 

"We have the right to use any means," Ramadan said, calling on Iraqis "to attack them in their homes." 

"We can have ... a suicide martyr that can kill 5,000 in one mission," he said. 

To avoid that future, Ramadan told the U.S.-led coalition to "pack your bags and leave us alone." 

Ramadan is believed to have coordinated the brutal suppression of the Shiite rebellion of 1991 in southern Iraq. 

Names of the dead were withheld pending notification of next of kin, Central Command said.