NAJAF, Iraq -- The brother of a cleric assassinated in a car bombing told 400,000 mourners Tuesday he blamed the U.S. occupation forces for the lax security that led to the attack at Iraq's most sacred Shiite mosque.

Also Tuesday, another car bomb struck police headquarters in central Baghdad, killing an Iraqi policeman and wounding at least 13 others in the latest attack apparently targeting Iraqis working with the American-led occupation.

L. Paul Bremer, the U.S. civilian administrator for Iraq, told a Baghdad news conference he shared the country's "anguish" over recent bombings, adding that "it's a fight we're now going to have to win here -- this fight against terrorism."

The U.S. military also reported the deaths of three more American soldiers -- two of them in the bombing of a convoy in southern Iraq.

'Pure blood'

At the funeral for Ayatollah Mohammed Baqir al-Hakim, his brother raged against the American troops and demanded they leave Iraq.

"The occupation force is primarily responsible for the pure blood that was spilled in holy Najaf, the blood of al-Hakim and the faithful group that was present near the mosque," said Abdel-Aziz al-Hakim, the ayatollah's brother and a member of the U.S.-picked Governing Council.

Men clad in white robes and dark uniforms brandishing Kalashnikov rifles stood guard along the roof of the gold-domed Imam Ali mosque, where the cleric was killed Friday in the bloodiest attack since the fall of Saddam Hussein. Accounts of the death toll ranged from more than 80 to more than 120.

Unable to recover al-Hakim's body after the blast, the family buried a coffin containing his watch, pen and wedding ring. The symbolic coffin was lowered below the parched ground in the 1920 Revolution Square, a cemetery set aside for martyrs in the Shiite Muslim uprising against British occupation. Al-Hakim's 15 bodyguards, who died with him in the car bombing, were buried in neighboring plots.

Mourners used empty cigarette packages to scoop up sand from the ground in the cemetery as keepsakes.

Al-Hakim has said he would not resign from the Governing Council but spoke with great anger about the American military's inability to pacify the country.

"This force is primarily responsible for all this blood and the blood that is shed all over Iraq every day," he said, voicing the frustrations of Iraqis throughout the country. The criticism could signal an open fissure in the historically cooperative relationship between the Shiites and the U.S.-led civilian and military occupation.

"Iraq must not remain occupied and the occupation must leave so that we can build Iraq as God wants us to do," he said.

A senior Iraqi police official told The Associated Press there were nine key suspects in the bombing in custody -- two Saudis, one Palestinian carrying a Jordanian passport and six Iraqis. All nine admitted ties to the al-Qaida terror network, the official said, speaking on condition of anonymity.

Besides the Imam Ali mosque, terrorist bombings in August also struck at the Jordanian Embassy and the U.N. headquarters in Baghdad.

Bremer, who cut short his vacation because of Friday's mosque bombing, told a Baghdad news conference that coalition forces want to share security responsibilities with Iraqis.

"We completely agree with the argument that we should find ways quickly to give Iraq and Iraqis more responsibility for security and indeed that is exactly what we are doing," he said.

Bremer, a former diplomat and counterterrorism expert, said there were already as many as 60,000 Iraqis involved in security or undergoing training.

"What we need at this point is better intelligence to find out where the terrorists are who are killing Iraqis," he said.

Earlier, the slain ayatollah's son warned that the country had entered a dangerous new era.

"Our injured Iraq is facing great and dangerous challenges in which one requires strength," Mohammed Hussein Mohammed Saeed al-Hakim said at one stop as the funeral procession moved from Baghdad to Najaf.

Car bomb

As the funeral was about to begin, the car bomb exploded outside police headquarters in Baghdad, killing one officer and wounding 13 others. An unknown number of bystanders also were wounded.

Acting police chief Hassan al-Obeidi, who has offices in the headquarters building and is closely associated with the occupation authority, was not harmed. There were U.S. soldiers in the nearby Baghdad police academy, but they also were unharmed.

Also Tuesday, a Black Hawk helicopter crashed south of Baghdad, killing one U.S. soldier and injuring a second in a "non-hostile" incident, U.S. military spokesman Spc. Anthony Reinoso said.

Two U.S. soldiers were killed and a third was wounded when a bomb went off Monday beside their convoy in southern Iraq, the military reported Tuesday.

The deaths raised to 286 the number of American forces killed in the Iraq war. Of those 148 died since May 1 when President Bush declared an end to major fighting. Seventy soldiers have died in combat since the declaration.