The U.S. solider was killed and two others wounded in a roadside bombing near Baqouba, 40 miles northeast of Baghdad. An American paratrooper was wounded in a fifth straight day of attacks in Fallujah, a Sunni Muslim city west of the capital.
Two Iraqi guards were killed in a bombing near an oil pipeline 150 miles north of the capital, U.S. officials said. Ten other members of the Iraqi Civil Defense Force were wounded by the blast.
Elsewhere, troops from the 101st Airborne Division killed two Iraqis and wounded a third after gunmen fired rocket-propelled grenades on a U.S. compound in the northern city of Mosul.
And in the capital, Iraqi police seized explosives from a car they said belonged to a Syrian and found a second improvised bomb in the same neighborhood. U.S. officials said they could not confirm the suspect was Syrian.
Meanwhile, at a donors conference in Madrid, U.S. officials and Iraq's interim leaders pushed for billions in foreign funding for reconstruction.
"It is our belief that reconstruction contributes to improving security conditions," Iraqi Foreign Minister Hoshyar Zebari told the conference.
In other developments:
The U.S. soldier's death brings to 105 the number of American troops killed by hostile fire since President Bush declared an end to major combat May 1. Since the war began, 340 Americans have perished.
The violence, six months after a U.S.-led force toppled Saddam Hussein's regime, has raised concern about prospects for a quick revival of Iraq's economy, despite the country's vast petroleum reserves.
Lt. Col. George Krivo, the U.S. command spokesman, said attacks on coalition forces have averaged about 26 a day over the past two weeks. About three-quarters of the attacks have occurred in an arc stretching from the west through Baghdad to the region north of the capital.
Also in Baqouba, 4th Infantry Division soldiers arrested two men believed responsible for some of the bombings and rocket-propelled grenade attacks against U.S. forces. A third suspect, thought to be the mastermind, eluded capture, officers said.
The American paratrooper, from the 82nd Airborne Division, was wounded Thursday by a roadside bomb in Fallujah, 40 miles west of Baghdad, U.S. officials said. It was the fifth attack against American forces in Fallujah since Sunday.
Ahead of the Madrid meeting, U.N. Secretary-General Kofi Annan and Secretary of State Colin Powell sought to lower expectations that Washington would come away with the entire $35.8 billion through 2007 it hopes to raise to jump-start Iraq's economic recovery.
Powell acknowledged "it may take time to meet the goal" of more than $55 billion set by the World Bank, which includes the Bush administration's nearly $20 billion pledge.
The centerpiece of the meeting is the creation of a new reconstruction fund managed by the World Bank, the United Nations and a committee of Iraqis. The fund is designed to lure donors wary of a U.S.-controlled fund.
France and Germany, leading opponents of the U.S.-led war, have both cited concerns about the slow pace of restoring Iraq's sovereignty for their refusal to pledge any new money now.
Despite the approval last week of a new U.N. resolution setting out Iraq's future course, Annan acknowledged that lingering divisions over Washington's role in running the country might deter some donors.
But in his opening remarks Thursday, Annan urged that such concerns be set aside, saying "the long-term challenge of reconstruction has to be faced by all of us."
So far, Japan has pledged $1.5 billion for 2004; South Korea has agreed to $200 million, and Canada, $150 million. The World Bank has said it will lend Iraq $3 billion to $5 billion over the coming five years.
Spain pledged $300 million through 2007 and Britain $439 million for 2004-2005. Both were firm supporters of the war.
The European Union's head office has limited its contribution to one year, promising $233 million.
A separate $20 billion package is now before the U.S. Congress, and will go mainly toward security in Iraq and resurrecting its oil industry.
Pressed why the Bush administration was not counting on Iraqi oil revenues to pay for reconstruction, Powell said the infrastructure "was more damaged than we expected, and not as a result of the war, but as a result of 30 years of abuse by this dictatorial regime."