Updated

A suicide bomber (search) blew himself up outside the house of two tribal leaders in what appears to be an attempt by insurgents trying to make good on their threat to target Iraqis who cooperate with U.S. forces.

The bomber walked up to the house of brothers Majid and Amer Ali Suleiman (search) in Ramadi (search), northwest of Baghdad, and detonated explosives strapped around his body, witnesses said.

Three guards were seriously injured but the brothers -- who are among the city's most prominent tribal leaders working with coalition forces -- escaped unhurt.

The bomber had approached the house earlier when the brothers were receiving callers, and was told to leave, the witnesses said.

Insurgents have repeatedly warned Iraqis not to cooperate with the Americans. The most recent threats were contained in pamphlets circulated in Ramadi and nearby Fallujah (search) by a purported coalition of 12 insurgent groups.

Ramadi and Fallujah are located in the Sunni Triangle, a major center of resistance to the U.S.-led occupation.

This is the second instance of a suicide bomber carrying out an attack with explosives on his body although several homicide car and truck bombings are not unknown. On Feb. 1 two men with explosives under their clothes blew up at a Muslim holiday celebration at the offices of two Kurdish parties in the northern town of Irbil, killing 109 people.

The two American soldiers were killed in an explosion outside Sinjar near the northern city of Mosul during an operation to dispose of ordnance, deputy operations chief Brig. Gen. Mark Kimmitt said.

Five soldiers were hurt in the blast, according to a statement issued by the U.S. military's Task Force Olympia. The statement said the soldiers were moving mortar shells and rocket propelled grenades from a storage area to a demolition point when the explosion occurred.

Elsewhere, U.S. and Iraqi forces deactivated several rockets that were primed for launch along a road toward the city of Baqouba, about 35 miles northeast of Baghdad.

Also Monday, defense officials in Washington said American forces in Iraq have detained one of the remaining most-wanted members of Saddam Hussein's government.

Muhsin Khadr al-Khafaji, No. 48 on the 55 most-wanted list, was turned over last weekend to U.S. troops in the Baghdad area, the officials said, speaking on the condition of anonymity. The officials did not say who turned him over.

In Baghdad, the U.N. experts met with several Iraqi politicians in a second round of meetings Monday to discuss the chances of holding early elections, a source of conflict between the United States and the influential Shiite clergy.

Team leader Lakhdar Brahimi met individually with several members of the U.S.-installed Governing Council to "gather facts," said Ahmad Fawzi, the team's spokesman.

The transfer of power is becoming a major headache for the U.S.-led coalition and the Governing Council.

The current U.S. plan is to choose legislators in regional caucuses, a move opposed by the country's most powerful Shiite cleric, Grand Ayatollah Ali al-Husseini al-Sistani. It is hoped that Brahimi's team, which arrived Saturday on what is believed to be a 10-day mission, will help break the impasse.

Brahimi is expected to travel to the Shiite holy city of Najaf to meet al-Sistani, but no date has been disclosed.

Also Monday, the U.S. military announced it has seized a letter from an Al Qaeda (search) courier written by an anti-American insurgent in Iraq, seeking Al Qaeda's help to spark a civil war between the country's two main Muslim sects, the Shiites and Sunnis.

The one of the 17-page letter indicates Usama bin Laden has made little headway in recruiting Iraqis for a holy war against America, raising questions about the Bush administration's contention that Iraq is the central front in the war on terror.

The letter was believed written by Abu Musab al-Zarqawi, a Jordanian suspected of Al Qaeda links. Al-Zarqawi is the chief suspect in several recent bombings, and the Bush administration cited his presence in Iraq as evidence of Iraq's terrorist connections even before the war.