Sunni Muslims protested the slaying of a tribal leader Friday, while a statement posted on the Internet said a car bombing that killed 11 people was in retaliation for the assassination of the respected sheik.

More than 200 members of the Batta tribe gathered at a mosque in northwestern Baghdad, carrying banners and chanting slogans to demand the resignation of the defense minister in the slaying of Khadim Sarhid al-Hemaiyem on Wednesday.

One of the slain man's brothers said a group of gunmen with Iraqi army uniforms and vehicles broke into al-Hemaiyem's home and killed him, three of his sons and his son-in-law. A spokesman for the Interior Ministry denied that government forces were involved.

Another one of al-Hemaiyem's sons was killed by men in uniform last month, family members said.

"We want the Arab League and the Sunni scholars to investigate," said Abdullah Jawad Khadim al-Battawi, a relative.

A statement from the little-known group Partisans of the Sunni claimed responsibility for a car bombing Thursday in Hillah, a mostly Shiite Muslim city 60 miles south of Baghdad, that killed 11 people and wounded 17.

"We have warned the (Shiites) to stop assassinations and detentions and torture," the statement posted Friday said. "You should know, your blood is no more dear than ours. You kill our men, we kill yours. You kill our sheiks, we kill yours. You started this war."

Also Friday, a prosecutor in Saddam Hussein's trial said a key witness in the case has died of cancer, but his testimony has already been taped for presentation in the proceedings, which are set to resume Monday.

Wadah Ismael al-Sheik died Oct. 27, four days after talking to court officials, said Jafaar al-Mousawi, the main prosecutor. He said the testimony at a U.S. detention center was "on the side of the victims."

Al-Sheik, was a senior Iraqi intelligence officer at the time of the Dujail massacre in 1982 that Saddam and seven other co-defendants are charged with.

If convicted, Saddam and the others could face the death penalty for their role in the 1982 killing of nearly 150 people from the mainly Shiite town of Dujail north of Baghdad after a failed assassination attempt.

Also on Thursday, a suicide bomber blew up his car outside a hospital south of Baghdad while U.S. troops handed out candy and food to children, killing 30 people and wounding about 40, including four Americans.

Three women and two children were among the dead in the attack outside the hospital in Mahmoudiya, a flashpoint town 20 miles south of Baghdad in the "triangle of death" notorious for attacks on Shiite Muslims, U.S. troops and foreign travelers.

A civil affairs team from the U.S. Army's Task Force Baghdad was at the hospital studying ways to upgrade the facility when the bomber struck just outside the guarded compound, a U.S. military statement said.

U.S. and Iraqi officials had been expecting a rise in violence before the Dec. 15 election, when voters will select their first fully constitutional parliament since the ouster of Saddam Hussein in 2003.

On Thursday, government spokesman Laith Kubba called the pre-election attacks "the last stand" of "Muslim extremists and Saddam's criminals," predicting they would rapidly lose support after establishment of a new government and a national reconciliation conference expected early next year.

More voters of the Sunni Arab minority, the backbone of the insurgency, are expected to vote this time, unlike the January balloting that many of them boycotted. Some Sunni insurgent groups have condemned the election and are expected to launch attacks to discourage a big turnout.

The United States hopes a big Sunni turnout will produce a broad-based government that can win the minority's trust, helping to take the steam out of the insurgency and hasten the day when American and other foreign troops can go home.

A U.S. statement said a soldier from Task Force Baghdad was killed Thursday in a single-vehicle accident involving his M-1 Abrams tank.