Early on Thursday, a US-led raid destroyed a Baghdad hide-out used by fighters associated with Musab al-Zarqawi, killing at least six men who opened fire on the troops, the military said. Troops seized weapons, ammunition and explosives.
Footage of the battle scene shot by Associated Press Television News showed large sections of the house razed and partial damage to the house next door.
The military said the house caught fire during the gun battle, causing weapons and ammunition inside to explode.
US troops leaving the scene loaded one Humvee with heavy machine-guns, rocket propelled grenades, rifles and belts of ammunition found inside the house.
An al-Qaida affiliate, the Ansar al-Sunnah Army, on Thursday claimed responsibility for a series of car bombs that killed dozens of Iraqi Shia Muslims over a 12-hour span in Baghdad.
The bombings in the Shia districts of Shula and Karradah appeared designed to stoke tensions between Sunni Arabs and Shia and push the country into civil war.
Despite the violence, there was some progress in an effort to reconcile the two embittered communities.
Representatives of the Sunni Arab minority, which is thought to form the core of the insurgency, endorsed a list of 15 representatives for a Shia-dominated committee drafting Iraq's constitution.
The decision removed the final obstacle hampering efforts to get Sunni Arabs onto the committee, which has until mid-August to draft a constitution.
The list of 15 Sunni Arabs was approved Thursday by a group of 50 Sunni Arab religious, tribal and political leaders who met in Iraq's old parliament building in downtown Baghdad. The 15 men and a single representative from Iraq's small Sabian community will sit on a special committee that will be formed in tandem with a 55-member body exclusively made up of elected legislators.
A woman argues with an Iraqi
soldier as her house is searched
The 71-member group will take decisions through consensus and send them to the other group for ratification. The clumsy setup was made necessary by a Sunni Arab decision to boycott the 30 January elections, leaving them with just 17 legislators in the 275-member parliament. An additional 13 Sunni Arabs also joined the parallel committee, but only in an advisory capacity.
The top US commander in the Gulf region told Congress on Thursday that he thought more foreign fighters were coming to Iraq.
"I believe there are more foreign fighters coming into Iraq than there were six months ago," said General John Abizaid. As to the overall strength of the fighters, he said it was "about the same" as six months ago, contradicting a claim by Vice President Dick Cheney last month that it was in its "last throes".
US military officials have said they think the fighters and their supporters number 12,000 to 20,000.
In other attacks, a remote-controlled-bomb exploded next to an Iraqi police patrol in Tuz Khormato, north of Baghdad, killing one police officer and wounding nine civilians, police Brigadier General Sarhad Qadr said. Tuz Khormato is 88km south of the northern city of Kirkuk.