Ambushes claimed the lives of four members of the U.S. military and five Iraqi contractors Monday, but U.S. officials said violence had not disrupted plans to hand over limited authority to an interim Iraqi government next week.

A patrol of four U.S. service members in Ramadi, a hotbed of Sunni Muslim resistance to the U.S. occupation, failed to report to commanders at a designated time Monday morning. A quick-reaction force sent to the city, 60 miles west of Baghdad, found the bodies of the Americans, who had been shot repeatedly in the head.

A videotape of the scene, broadcast throughout the day on Arabic-language satellite channels, showed the victims lying in what appeared to be the courtyard of a compound without standard-issue body armor, helmets or rifles. Brig. Gen. Mark Kimmitt, the chief U.S. military spokesman in Iraq, declined to offer details about the incident pending notification of the dead Americans' families.

The Associated Press later identified the four as Marines. Citing the U.S. command, the AP also said a mortar attack Monday in north-central Baghdad killed one U.S. soldier and wounded seven.

About 30 miles south of Mosul in northern Iraq, a roadside bomb exploded near a convoy carrying Iraqi contractors. Five Iraqis, who military officials said worked for a foreign company, were killed and two were wounded.

The deaths came as U.S. occupation officials emphasized that the gradual transfer of political authority to an interim Iraqi government, underway for weeks, had not been deterred by the months-long wave of violence. U.S. officials have blamed the near-daily car bombings, kidnappings and ambushes on a diffuse insurgency intent on destabilizing the country before an interim administration officially assumes political authority on June 30.

Daniel Senor, chief spokesman for the U.S.-led Coalition Provisional Authority, said he expected all 26 government ministries to be in the hands of Iraqis by the end of the week. But how the U.S. military, which plans to maintain 138,000 troops in the country through the handover, will operate under the new government remains largely unresolved.

U.S. military officials said Monday that, given the inability of fledgling Iraqi security forces to subdue the insurgency, there would be little difference in the scope of U.S.-led military operations after the transfer date.

"The character is not going to change dramatically on the first day of July militarily the way it is dramatically changing politically," Kimmitt said. "I think all of us understand that it will be some time before those Iraqi security forces can take on the burden and the responsibility. And it will happen differently in different portions of the country."

Meanwhile, the Iraqi official responsible for organizing a national conference next month that will select a consultative assembly denied published reports that he had invited Moqtada Sadr, the stridently anti-American Shiite Muslim cleric, to participate in the process.

Sadr is the leader of an outlawed militia, made up mostly of poor Shiites, that rose up against the occupation in April. He faces an Iraqi arrest warrant on charges that he conspired in the April 2003 murder of a rival cleric. U.S. officials said Monday he would likely have to resolve the legal matter before being allowed to participate in politics.

But Fouad Masoum, who heads the organizing committee for the conference, did not rule out the possibility of including a religious figure who represents many of the same people who follow Sadr.

"We have to differentiate between Moqtada Sadr on one side and the Sadr trend on the other," Masoum said.

Special correspondent Omar Fekeiki contributed to this report.

Video footage shows the bodies of members of a U.S. patrol ambushed in Ramadi, a center of Iraqi resistance to the occupation.