Thousands of American troops searched on Sunday for three U.S. soldiers missing in Iraq after an ambush in which al Qaeda said it seized "crusader" forces, while a suicide bomber killed 50 people in the Kurdish north.

A group led by al Qaeda, said in an Internet posting it was holding soldiers who survived an attack south of Baghdad in which the U.S. military said four U.S. troops and an Iraqi army translator were killed.

That attack and the suicide truck bombing came as President George W. Bush deploys 30,000 more U.S. troops due in Iraq in June.

Last June, al Qaeda abducted two U.S. soldiers in the same area where the patrol of seven U.S. soldiers and one Iraqi army interpreter were ambushed on Saturday. Their badly mutilated bodies were found days later.

Iran and the United States, making a cautious diplomatic rapprochement, said they would hold talks in Baghdad aimed at stabilizing Iraq.

In Baghdad, a car bomb killed 12 people in a popular market, police said.

Kurds fear violence

As U.S.-led troops backed by helicopters and jets combed the ambush area south of the capital known as the Sunni "Triangle of Death," a truck bomb killed 50 people and wounded 70 in the northern town of Makhmour, the governor said. It was the second attack on Kurdish areas in Iraq in four days.

Makhmour is just outside the autonomous Kurdish region, but Kurds want to include it in the region in a future settlement.

A truck bomb on Wednesday in the city of Arbil, capital of Kurdistan, killed 15 people and wounded more than 100 in an attack claimed by al Qaeda that sparked fears violence engulfing much of Iraq was spreading to the relatively peaceful region.

PHOTO CAPTION

U.S. soldiers comfort each other at a memorial service for an U.S. Army Chief Warrant Officer in Mahmudiya April 26, 2007. (Reuters)