An estimated 50,000 Shiite Muslim (searchfaithful descended on this holy city Friday for ceremonies marking the 40th day since the car bomb assassination of revered cleric Mohammed Baqir al-Hakim (search).

The crowd marched into the city chanting anti-Saddam Hussein slogans, some people beating their chests in a traditional Shiite gesture of mourning. Others chanted pledges of support for Abdel-Aziz al-Hakim (search), the dead cleric's brother and a member of the U.S.-appointed Governing Council.

"The enemies of the Iraqi people from the remnants of the former regime and their allies are criminals and terrorists and they are determined to commit their crimes against the Iraqi people, who will not remain silent," said al-Hakim.

He also was critical of the U.S.-led occupation authority's attempts to pacify the country, which is still rattled by violence nearly six months after Saddam was ousted.

"The adopted policies by the occupation forces in dealing with the security situation are wrong and must be reconsidered and abandoned. Political parties must be counted on to handle this difficult task," he said.

Iraqi police, the Badr Brigade -- the banned military wing of the Supreme Council for the Islamic Revolution in Iraq, and uniformed soldiers of the Patriotic Union of Kurdistan provided security at the memorial services. The slain al-Hakim founded SCIRI while in Iranian exile. His brother has since taken over leadership.

Black flags of mourning were strung on buildings throughout Najaf, the site of the Imam Ali shrine, the holiest Shiite location in Iraq.

Al-Hakim was killed in a car bombing Aug. 29 in Najaf. The attack left more than 80 others dead and more than 140 wounded in the single deadliest attack under the U.S.-led occupation.

Speaking at al-Hakim's grave site, Jalal Talabani, head of the PUK and member of the Governing Council described al-Hakim's death as a "national disaster for Iraq and Muslims" and a huge loss for Iraqis. He called for unity between Sunnis and Shiites.

Mohsen Abdul Hamid, another member of the Governing Council, warned of plans to sow discord between Shiites and Sunnis and called for strong opposition to planting seeds of discord.

Overnight, the U.S. military reported soldiers of the 101st Airborne Division witnessed two Iraqis killed as they were trying to place a roadside bomb in Kirkuk, 145 miles northeast of Baghdad.

On Thursday, Lt. Gen. Ricardo Sanchez, U.S. commander in Iraq, said between three and six American soldiers are killed and another 40 wounded every week in Iraq by an enemy that has become more lethal and sophisticated since the fall of Baghdad in April.

U.S. soldiers are still facing 15-20 attacks a day, including roadside bombs, Sanchez said. Seven to 10 attacks a day involve small groups of fighters.

"They're getting attacked every day," Sanchez said of his soldiers. "I'm having soldiers wounded at a rate of about 40 a week and getting killed anywhere from three to six soldiers a week."

Most attacks occur in Baghdad and the surrounding Sunni Muslim stronghold to the west and north of the capital, although it's unclear whether Iraqi or foreign forces account for the majority.

"The enemy has evolved -- a little bit more lethal, a little more complex, a little more sophisticated, and in some cases, a little bit more tenacious," Sanchez said.

Russian President Vladimir Putin, meanwhile, suggested that the Iraqi people remained suspicious of the U.S.-led occupying forces.

Iraqis "have more confidence in that country's traditional partners than in some who are controlling the country today," Putin told a World Economic Forum in Moscow on Friday.

Russia strongly opposed the U.S.-led war but has expressed a willingness to work with the United States in the country's reconstruction effort.