Prime Minister Ayad Allawi made an unusually strong warning to Iraq's neighbors to crack down on insurgents infiltrating from their territory, saying that Iraq's patience was wearing thin. Al-Qaeda, meanwhile, claimed responsibility for a bold attack on US troops.
Iraqi officials have repeatedly accused Syria and Iran of supporting the insurgents waging a campaign of violence against American forces and Allawi's US-backed government. Both countries have denied helping militants or allowing them to cross the borders into Iraq.
But Allawi's comments on Friday to Baghdad's Al-Iraqiya television were among his toughest yet. "Some countries are hosting people who are involved in harming the Iraqi people," he said, without naming any nations. "Harming Iraq and its people is not allowed."
He said his government had contacted the countries and was waiting for their reply. "According to the answers we will decide what the next step will be," he said.
"Iraq is not a weak country. Iraq is passing through a difficult period but Iraq can respond in a strong way if needed," he said. "Patience has limits and it is beginning to run out."
In new violence, a US Marine assigned to the I Marine Expeditionary Force was killed in action on Friday during security operations in the Al Anbar Province, the Marines said in a release, which did not provide any other details.
Meanwhile, the US first Infantry Division detained 49 suspected guerrillas during a midnight raid in the town of Duluiyah, 72km north of Baghdad, it said on Friday. The sweep appeared to be the latest in a series of anti-insurgency campaigns in the so-called Sunni Triangle in central Iraq.
Al-Qaeda in Iraq, led by the country's most wanted terrorist Abu Musab al-Zarqawi, claimed responsibility for a well-coordinated attack on Wednesday on a US post in the northern city of Mosul. The US military said one American soldier and 25 insurgents were killed in the battle.
The militants, however, claimed they had suffered no casualties.
"We, al-Qaeda in Iraq, claim responsibility for the battles of Mosul, may God cleanse it from the impurities of the infidels," said a statement posted on a Web site that often carries militant claims.
Wednesday's attack began with a massive truck bomb exploding just outside a US checkpoint, followed by attacks by squads of 10 to 12 insurgents.
A Stryker vehicle reinforcing the Americans was hit by a roadside bomb and a second car bomb. US forces then called in airstrikes by F-18 and F-16 fighter jets, which launched three Maverick missiles and conducted several strafing runs.
In new violence, a car bomb exploded next to a taxi carrying Iraqi national guardsmen in the town of Beiji, 249km north of Baghdad. A passenger car, which happened to be passing by at that moment, absorbed the brunt of the blast, killing its two occupants while five guardsmen were wounded, Major Neil O'Brien said.
North of Fallujah, a body of an Iraqi national guardsman was found with a handwritten note pinned to it saying: "This is the fate of anyone who collaborates with the occupation forces."
Insurgents have intensified their strikes in a campaign to disrupt the Jan. 30 general elections for a constitutional assembly that will set up the next government and write a new constitution. Rebels have targeted members of the interim government's security forces, perceived as collaborators with American occupiers.