Shiite politicians raged at the United States and halted negotiations on a new government Monday after a military assault killed at least 16 people in what Iraqis claim was a mosque. Fresh violence erupted in the north, with 40 killed in a suicide bombing.

Iraqi men survey the site of a U.S. backed raid on a Shiite neighborhood in Baghdad Monday March 27, 2006 in Baghdad. At least 16 Iraqis were killed in a U.S. backed raid in a Shiite neighborhood of the capital on Sunday evening. [AP]

The firestorm of recrimination over Sunday's raid in northeast Baghdad will likely make it harder for Shiite politicians to keep a lid on their more angry followers as sectarian violence boils over, with at least 151 dead over the two-day period. A unity government involving Shiites, Sunnis and Kurds is a benchmark for American hopes of starting to withdraw troops this summer.

There were numerous conflicting statements from Iraqis and the Americans about the raid. Iraqi police, Shiite militia officials and major politicians have all said the structure attacked was the al-Mustafa mosque. But the U.S. military disputed this, saying no mosques were entered and that the raid targeted a building used by "insurgents responsible for kidnapping and execution activities."

In a conference call with reporters early Tuesday, Lt. Gen. Peter Chiarelli, deputy commander in Iraq, and Maj. Gen. J.D. Thurman, commander of the 4th Infantry Division, which is in control of Baghdad, said 25 U.S. forces were in a backup role to 50 Iraqi Special Operations troops.

The mission, the generals said, was developed by the Iraqis on their intelligence that an Iraqi dental technician, kidnapped 12 hours earlier because he could not come up with $20,000, was being held in what they called an office complex.

"It's important to remember we had an Iraqi unit with us, an Iraqi unit of 50 folks and they told us point blank that this was not a mosque," Chiarelli said. "It's not Mustafa mosque. Mustafa mosque is located six blocks north on our maps of this location."

Associated Press reporters who visited the scene of the raid identified it as a neighborhood Shiite mosque complex. Television footage taken Monday showed crumbling walls and disarray in a compound used as a gathering place for prayer. It was filled with religious posters and strung with banners denouncing the attack.

In an earlier statement, the military said the building had been under U.S. observation for some time.

The statement said gunmen opened fire as Iraqi special operations troops closed in. It said the troops then killed 16 insurgents and wounded three "during a house-to-house search," detained 18 men, found a significant weapons cache and freed the hostage.

"In our observation of the place and the activities that were going on, it's difficult for us to consider this a place of prayer," said Lt. Col. Barry Johnson, a U.S. military spokesman.

For their part, Iraqi police said gunmen fired on the joint U.S.-Iraqi patrol from a position in the neighborhood but not from the mosque.

Police and representatives of radical Shiite cleric Muqtada al-Sadr, who holds great sway among poor Shiites in eastern Baghdad, said all those killed were in the complex for evening prayers and none was a gunman. Police put the death toll at 17 ¡ª seven members of al-Sadr's militia, seven civilians and three Shiite political activists.

Video from Sunday night showed male bodies with gunshot wounds on the floor of what was said by the cameraman to be the imam's living quarters, attached to mosque itself. The compound, once used by Saddam Hussein's government, consists of a political party office, the mosque and quarters for the imam.

The video also showed 5.56 mm shell casings scattered on the floor. U.S. forces use that caliber ammunition and have provided it to Iraqi special operations troops.

But Chiarelli said someone had gone into the scene of the raid to make it look as though there had been an assault without cause.

"After the fact someone went in and made the scene look different than it was," Chiarelli said.

Neither general would say who might have carried out such a charade. Nor would they say what they had learned about the men detained in the operation, citing intelligence strictures.

Interior Minister Bayan Jabr angrily rejected the U.S. account and demanded a "clear explanation."

"Entering the Mustafa Shiite mosque and killing worshippers was unjustified and a horrible violation from my point of view," Jabr said on the Al-Arabiya TV network. "Innocent people inside the mosque offering prayer at sunset were killed."

President Jalal Talabani, a Kurd, said he called U.S. Ambassador Zalmay Khalilzad and that they decided to form an Iraqi-U.S. committee to investigate.

"I will personally supervise, and we will learn who was responsible. Those who are behind this attack must be brought to the justice and punished," Talabani said.

The United Iraqi Alliance, the largest Shiite bloc in parliament, canceled Monday's session of negotiations to form a new government because of the raid, said lawmaker Jawad al-Maliki.

"We suspended today's meetings to discuss the formation of the government because of what happened at the al-Moustafa mosque," al-Maliki said, adding that the alliance was expected to decide Tuesday when to resume the talks.

The Baghdad governor said he cut ties with U.S. forces and diplomats. And all 37 members of the Baghdad provincial council suspended cooperation with the United States in reconstruction projects planned for the remainder of the year, as well as political and security coordination, said council chairman Moeen al-Khadimi.

He said the local government would try to rely instead on the budget allocated to it by the Finance Ministry and on the money that comes from donor countries.

The U.S. statement describing the kidnappers and killers they were targeting as "insurgents" was unusual because the operation took place at a Shiite facility. The insurgents who have been carrying out nearly daily bombings are Sunnis, while those believed responsible for execution-style slayings are primarily Shiite militias or death squads working inside the Shiite-dominated Interior Ministry, which runs the police.

"We don't know who they were," Chiarelli said. "They were terrorists, insurgents, you can call them what you will."

Monday's major suicide bombing took place at an Iraqi army recruiting office near the gate of a U.S.-Iraq military base about 20 miles east of Tal Afar, an ancient city not far from the Syrian border.

The bomber, wearing an explosives vest, struck shortly after noon, killing at least 40 Iraqis and wounding 30 others, the Iraqi Defense Ministry said.

In yet one more gruesome discovery ¡ª a nearly daily occurrence since the Feb. 22 bombing of a Shiite shrine in Samarra ¡ª 29 more bodies were found, nine with a noose around their necks.

The country's senior Shiite politician, Abdul-Aziz al-Hakim, told CNN that the shrine bombing "was similar to what happened on 9/11 in the U.S."

He said it's now much more difficult to control the streets, and that Shiites had earlier exercised restraint in the wake of attacks by Sunni insurgents.

"For three years we've been burying the slaughtering, killing, explosions, attacking of our scholars, our mosques, our facilities, our pilgrims, our barbers, our bakers, our innocents," al-Hakim said. "We are always speaking to people to restrain themselves and calm down."