The contractor was employed by Kellogg Brown & Root, a subsidiary of Halliburton, a Houston-based oilfield-services and construction company. Halliburton, the former company of Vice President Dick Cheney, has major contracts for reconstruction in both Iraq and Afghanistan.
Maj. Brian Luke, of the 4th Infantry Division, said the five- vehicle convoy was traveling from Baghdad when it was attacked. Insurgents have increasingly been using roadside bombs detonated by remote control to attack American forces.
Kellogg Brown & Root has been doing work at the Baiji refinery and pipeline terminus about 30 miles north of Tikrit, the hometown of deposed dictator Saddam Hussein, about 125 miles north of Baghdad.
The military said the destination of the convoy was not immediately known, and that the name of the civilian was being withheld until relatives were notified.
Lt. Col. William MacDonald, also of the 4th Infantry, said the contractor died after being taken to a U.S. military field hospital at an air base north of Tikrit.
In other developments:
In the past week, the Gen. Richard B. Myers, chairman of the U.S. Joint Chiefs of Staff; Lt. Gen. Ricardo Sanchez, the commander of U.S. ground forces in Iraq; and Deputy Defense Secretary Paul Wolfowitz all have made statements suggesting foreign terrorists were an increasing problem for American forces.
"No one I think believes that here is not an infiltration, a continued infiltration, of foreign fighters into that country," Meyers said Tuesday. He pointed to a camp in Iraq where some 75 foreign fighters were killed several weeks ago.
However, Army spokesman Capt. Mike Calver said the existence or depth of foreign intervention was not clear. "We suspect that this may be true, but I don't think we can quantify at this time how many attacks are carried out by al Qaeda or Saddam loyalists," he said.
A second commander in the region around Ramadi, the Anbar provincial capital 60 miles west of Baghdad, said disgruntled residents — some of them religious people offended by the presence of non-Muslim U.S. forces — and former Baath Party members were behind the attacks on Americans.
Dozens of Iraqis interviewed in the region — many of whom said they had links to the resistance — insisted none of the attacks on Americans was the work of foreigners. They said that most of the 4,000 to 6,000 Arab fighters who flooded into the country before the war began have either been killed or fled.
Those interviewed said U.S. officials wanted show the world that Iraqis supported the American occupation and therefore were blaming foreign fighters for the insurgency.
"They are claiming there are al Qaeda fighters in order to justify to their people their invasion and occupation of Iraq," said Sheik Diyab Younis Zo'ebi, 62, a tribal leader in Fallujah, about 18 miles east of Ramadi.
"We and al Qaeda are two opposite things. Bin Laden (fighters) cannot come into Iraq…because we will not let them. They are enemies of our religion," he said.
An active connection between Saddam and al Qaeda was one U.S. justification for the war. No evidence has been found to confirm that allegation.
But there is ample evidence of a reservoir of resentment against Americans.
In one sign of frustration, demonstrators Monday destroyed an Iraqi police car near the city of Fallujah, where U.S. forces have been training local police officers, reports CBS News Correspondent Byron Pitts.
The crowd marched through the town, where Americans have come under fire almost daily, screaming, "No God but God" and "America is the enemy of God."