BAGHDAD - Iraq's prime minister said yesterday that a U.S. Senate proposal to split the country into regions according to religious or ethnic divisions would be a "catastrophe."

The Kurds in three northern Iraqi provinces are running a virtually independent country within Iraq, while nominally maintaining relations with Baghdad. They support a formal division. But both Sunni and Shiite Muslims have reacted with extreme opposition to the Senate proposal.

The majority Shiites, who would retain control of major oil revenues under a division of the country, oppose the measure because it would diminish the territorial integrity of Iraq, which they now control. Sunnis would control an area with few if any oil resources. Kurds have major oil reserves in their territory.

The nonbinding Senate resolution calls for Iraq to be divided into federal regions under control of the three communities in a power-sharing agreement similar to the one that ended the 1990s war in Bosnia. Sen. Joseph R. Biden Jr. (D., Del.), who is running for president, was a prime sponsor of the measure.

"It is an Iraqi affair dealing with Iraqis," Prime Minister Nouri al-Maliki told the Associated Press on a return flight to Baghdad from New York where he appeared at the U.N. General Assembly. "Iraqis are eager for Iraq's unity. . . . Dividing Iraq is a problem, and a decision like that would be a catastrophe."

The comments were Maliki's first since the measure passed the Senate on Wednesday.

Iraq's constitution lays down a federal system, allowing Shiites in the south, Kurds in the north and Sunnis in the center and west of the country to set up regions with considerable autonomous powers.

Nevertheless, ethnic and sectarian turmoil have snarled hopes of negotiating such measures, especially given deep divisions on sharing the country's vast oil resources. Oil reserves and existing fields would fall mainly into the hands of Kurds and Shiites if such a division were to occur. So far there has been no agreement on a broader sharing of those revenues.

On Thursday, Iraqi Vice President Adel Abdul-Mahdi, a Shiite, said decisions about Iraq must remain in the hands of its citizens. And a spokesman for radical Shiite cleric Muqtada al-Sadr demanded the Maliki government reject the proposal.

A spokesman for Grand Ayatollah Ali al-Sistani, the Shiite spiritual leader, dismissed the proposal during a sermon yesterday in Karbala.

Secretary of State Condoleezza Rice said Tuesday that the administration supports a federal Iraq, but it is a "sensitive issue best left to the Iraqis to address at their own pace."

Meanwhile, Iraqi police and witnesses said U.S. troops backed by helicopter gunships raided an apartment building at 2 a.m. yesterday in southern Baghdad, killing 10 civilians and wounding 12. The U.S. military said it was checking into the report.

In violence north of Baghdad, at least six people were killed when four gunmen with full beards and wearing military uniforms barged into a busy cafe late Thursday as people were playing a popular game to celebrate the end of the Islamic holy month of Ramadan.

The six killed included three off-duty police officers. Eight others were wounded, an officer said.

On Other Fronts

The United States and Iraq are focusing on five incidents in which Blackwater USA guards killed civilians in Iraq this year. Those incidents are at the core of an investigation ordered last week by Secretary of State Condoleezza Rice.

A federal judge refused yesterday to dismiss a defamation case against Rep. John P. Murtha (D., Pa.), ordering him to give a sworn deposition in the case. Marine Corps Staff Sgt. Frank Wuterich says the 16-term congressman falsely accused him of "cold-blooded murder and war crimes" in connection with the 2005 deaths of Iraqi civilians in Haditha.

U.S. Army Spec. Jorge G. Sandoval, 22, was acquitted on charges he killed two unarmed Iraqis. He was convicted of a lesser charge of planting evidence on one of the bodies to cover up the crime. He was to be sentenced today.

American-led forces on Tuesday killed one of the most important leaders of al-Qaeda in Iraq, a Tunisian named Abu Osama al-Tunisi, the U.S. military announced. Tunisi was believed connected to the kidnapping and killings last summer of U.S. soldiers.

- Wire services