Meanwhile, in Baghdad, U.S. soldiers and Iraqi police surrounded the residence of Iraqi politician Ahmad Chalabi on Thursday, and an aide said the troops raided the house ostensibly to search for fugitives.
The aide, Haidar Musawi, accused the Americans of trying to pressure Chalabi, a longtime Pentagon favorite who has become openly critical of U.S. plans for how much power to transfer to the Iraqis on June 30.
He said the Americans also raided offices of Chalabi's Iraqi National Congress.
"The aim is to put political pressure," Musawi told The Associated Press. "Why is this happening at a time when the government is being formed?"
There was no comment from the U.S. military press office. Police sealed off the residence in the city's fashionable Mansour district and would not allow reporters to approach. At least two Humvees could be seen, with a dozen U.S. troops milling about.
In other developments:
U.S. officials reported no American casualties during engagements in the Shiite holy cities of Karbala and Najaf. But assailants with hand grenades killed a U.S. soldier and wounded three in central Baghdad early Thursday, the military said.
The disputed attack Wednesday happened about 2:45 a.m. in a desert region near the border with Syria and Jordan, according to Lt. Col. Ziyad al-Jbouri, deputy police chief of Ramadi, the provincial capital about 250 miles to the east. He said 42 to 45 people died, including 15 children and 10 women. Dr. Salah al-Ani, who works at a hospital in Ramadi, put the death toll at 45.
Associated Press Television News footage from the area near the Syrian border showed a truck containing bloodied bodies, many wrapped in blankets, piled one atop the other. Several were children, one of whom was decapitated. The body of a girl who appeared to be less than 5 years of age lay in a white sheet, her legs riddled with wounds and her dress soaked in blood.
Whether it was a mistake or not, the pictures are adding fuel to the fires of anti-American anger, reports CBS News correspondent David Hawkins from Baghdad.
The area, a desolate region populated only by shepherds, is popular with smugglers, including weapons smugglers, and the U.S. military suspects militants use it as a route to slip in from Syria to fight the Americans. It is under constant surveillance by American forces.
Military officials in Washington refused to address the question of whether anyone from a wedding party was among the people killed.
In a statement, the U.S. Central Command said coalition forces conducted a military operation at 3 a.m. against a "suspected foreign fighter safe house" in the open desert, about 50 miles southwest of Husaybah and 15 miles from the Syrian border.
The coalition troops came under hostile fire and "close air support was provided," the statement said. The troops recovered weapons, Iraqi and Syrian currency, some passports and some satellite communications gear, it said.
APTN video footage showed mourners with shovels digging graves over a wide dusty area in Ramadi, the provincial capital where bodies of the dead had been taken to obtain death certificates. A group of men crouched and wept around one coffin.
Iraqis interviewed on the videotape said revelers had fired volleys of gunfire into the air in a traditional wedding celebration before the attack took place. American troops have sometimes mistaken celebratory gunfire for hostile fire.
Al-Ani, the doctor, said American troops came to investigate the gunfire and left. However, al-Ani said, helicopters later arrived and attacked the area. Two houses were destroyed, he said.
"This was a wedding and the (U.S.) planes came and attacked the people at a house. Is this the democracy and freedom that (President) Bush has brought us?" said a man on the videotape, Dahham Harraj. "There was no reason."
The strike, widely reported in Iraq and the Middle East as an attack on a wedding party, comes at a time when American prestige is under fire as the United States tries to stabilize this country before the June 30 transfer of sovereignty are foundering.
Anti-American sentiment has risen following last month's bloody Marine siege of Fallujah, a Shiite Muslim uprising and the scandal over treatment of Iraqi detainees at Abu Ghraib prison.
As for Chalabi, U.S. officials, speaking on condition of anonymity, have accused him of trying to interfere with an investigation into alleged corruption of the U.N.-run oil-for-food program, in which Saddam Hussein's government was allowed to sell oil despite international sanctions to buy food and humanitarian supplies.
Critics allege that former regime officials, in collusion with U.N. figures, skimmed a fortune off the revenues.