BAGHDAD - The insurgent coalition that includes al-Qaeda in Iraq asserted responsibility yesterday for the ambush south of Baghdad that left four U.S. soldiers and an Iraqi interpreter dead and three other American soldiers missing.

A brief statement purporting to be from the Islamic State of Iraq, an umbrella organization that includes al-Qaeda in Iraq, appeared on insurgent Web sites a day after the fiery attack in the rural terrain near Mahmoudiya. The statement praised the insurgents for their "blessed operation" involving a "clash with a convoy of crusaders in Mahmoudiya," but offered few details and no evidence, such as photographs or video, to verify the claims.

"We will give you the full details about this blessed operation as soon as it comes," the statement said.

About 4,000 U.S. soldiers, backed by Iraqi troops, searched homes, palm groves and farmland yesterday for the three missing soldiers. The attack occurred in an area, known as the Triangle of Death, that has long been considered a breeding ground for Sunni insurgents.

Iraq's deputy prime minister, Barham Salih, told CNN that "indications are that al-Qaeda and its affiliate organizations are responsible for this attack."

The American soldiers were not moving in a convoy at the time of the attack, but rather parked in two Humvees in an area 12 miles west of Mahmoudiya, attempting to prevent insurgents from laying down roadside bombs, said a U.S. military official who spoke on condition of anonymity. Americans frequently conduct such missions, known as "overwatch," to monitor suspected trouble spots at night. It is unusual to have American soldiers out on patrol in as few as two vehicles.

"This was not a convoy; they weren't roving; they were in a fixed location," the official said. "Their mission was to counter the emplacement of improvised explosive devices."

The coordinated attack began when a roadside bomb exploded near the soldiers, then continued with gunfire, officials said. The two vehicles went up in flames and were spotted 15 minutes later by a surveillance drone, after a nearby unit that heard explosions could not get in contact with the Humvees. The extent of the damage made it difficult to identify the slain soldiers.

Yesterday, Maj. Gen. William Caldwell, the top American military spokesman in Iraq, said the interpreter and four soldiers had been killed. Military officials have so far been able to identify all but one of the soldiers, Caldwell said.

Talk of the abductions spread quickly throughout the streets and mosques in Mahmoudiya. Residents said the soldiers had gone through hundreds of houses, shops and farms, through villages and along canals and rivers, while attack helicopters and surveillance drones buzzed overhead.

Ahmad Ali, 32, a high school teacher in Mahmoudiya, said he believed the missing soldiers must still be in the area, perhaps in tunnels built by insurgents, because of the massive American presence surrounding the area. The al-Qaeda in Iraq statement, devoid of details, suggested "the leadership cannot contact its members in the city," he said.

The manhunt unfolded on one of the deadliest days in the country in recent weeks, with at least 126 people killed or found dead - including two American soldiers who died in separate bombings.

A suicide truck bomb tore through the offices of a Kurdish political party in northern Iraq, killing 50 people, and a car bombing in a crowded Baghdad market killed an additional 17.

The suicide bomber in northern Iraq slammed a truck into local offices of the Kurdistan Democratic Party, which is headed by Massoud Barzani, leader of the autonomous Kurdish region.

Cars were charred and crushed by the blast in Makhmur, a town with a substantial Kurdish population just south of the autonomous Kurdish-controlled areas.

At least 50 people were killed and 115 were wounded, including the city's mayor, Abdul Rahman Delaf, who also is a prominent Kurdish writer, and the director of the KDP office.

"Makhmur is an open, peaceful area, and al-Qaeda is trying to destabilize it by causing fighting between Arabs and Kurds," said Qassim Amin, whose son and daughter - who both work for the party - were injured.

The attack was the second suicide bombing in Kurdish areas in five days. On Wednesday, a suicide truck bomber devastated the security headquarters in Irbil - the capital of the Kurdish autonomous region and one of Iraq's most peaceful cities - killing at least 15 people and wounding more than 100. The Islamic State of Iraq also claimed responsibility for that blast.

In Baghdad, a parked car exploded yesterday near the popular Sadriyah market in the center of the city, killing at least 17 people and wounding 46, police said.

Sadriyah has been hit by several blasts usually blamed on Sunni insurgents, who are suspected of targeting commercial areas to kill large numbers of people.

On April 18, 127 people were killed in a car bombing in the same area - one of four bombings that day that killed a total of 183 people.

The U.S. soldiers who died yesterday were killed in bombings in Anbar and Salahuddin provinces, the military said.

Iraqis Reach a Political Deal

Iraqi Prime Minister Nouri al-Maliki has agreed to give Sunnis a bigger role in security operations in their areas, lawmakers said yesterday. The deal staves off a threatened Sunni walkout that could have toppled the Shiite leader's embattled government.

The agreement with Iraq's Sunni vice president could help assuage long-standing Sunni complaints that Shiite-dominated security forces unfairly target Sunni areas but avoid cracking down on Shiite militias linked to influential politicians.

The Bush administration has been pushing Maliki for months to reach out more to the once-dominant Sunni Arab minority, giving them a genuine role in the running of the country as part of a wider drive toward national unity that officials hope will reduce the country's rampant violence.

The lawmakers said the deal was reached in talks between Maliki and Vice President Tariq al-Hashemi, who had threatened to withdraw his bloc from the government if Sunni demands were not met. His bloc controls 44 of the 275 National Assembly seats.

Under the terms, Hashemi will have an "executive role" in the fight against insurgents in Sunni areas inside and outside Baghdad, the lawmakers said. Maliki remains the armed forces' commander-in-chief, they said. However, the agreement was described by lawmakers as an understanding rather than a formal pact, and similar arrangements have broken down in the past.

Sunni-Shiite reconciliation is a key benchmark the United States wants Maliki's government to meet at a time of growing congressional opposition to the war. Other benchmarks include a new law to distribute oil revenues equitably among all Iraqis and amendments to the constitution to address Sunni demands.

- Associated PressEndText

This article includes information from the Associated Press.