BAGHDAD - Tens of thousands of Shiite pilgrims converged on a golden-domed shrine in northern Baghdad, some beating their heads and chests with their hands and others dancing in a circle to honor an eighth century saint known for his ability to hide his anger.

The procession took place under tight security with guards checking each pilgrim as they reached the green iron gates of the Imam Moussa al-Kadhim mosque and a citywide driving ban in effect until early Saturday to prevent suicide car bombings.

Shiite religious festivals have become easy targets for Sunni insurgents trying to provoke an all-out civil war between Iraq's main Muslim groups. This festival was struck by tragedy two years ago, when an estimated 1,000 pilgrims were killed in a stampede after reports spread that a suicide attacker was among them -- the biggest single loss of life since the U.S.-led war began in March 2003.

Still, women shrouded in black abayas and men of all ages walked for hours, some even days, from holy cities south of Baghdad and the volatile Diyala province to the north to reach the mosque with twin golden domes and four minarets that sparkled in the unrelenting summer sun.

"I have come here to get the blessing of the martyr imam and to challenge the terrorism of the Wahhabists," said Hussein Mizaal, a 21-year-old college student from southeastern Baghdad. "We are not afraid of anyone except God. Our faith is getting stronger despite their mean attacks," he said in reference to the austere Wahhabi sect of Sunni Islam practiced in Saudi Arabia.

The ceremony is not one of the most important in the Shiite faith but has gained significance in Iraq because they were banned under Saddam Hussein's Sunni-dominated regime.

Imam Moussa ibn Jaafar al-Kadhim, who died in the year 799, was the seventh of 12 principal Shiite saints, known for his patience and his ability to suppress his anger. The mosque was built around what were believed to be the tombs of al-Kadhim and his grandson.

Crowds waved green Islamic flags and the Iraqi standard as they massed around the mosque in the Kazimiyah neighborhood. Green coffins symbolizing the imam were carried overhead and pilgrims reached out to touch the walls.

Tents strung with colored lights and flowers provided shade and water, while vendors offered pilgrims egg sandwiches, soup, yoghurt and tea. Many pilgrims had arrived a day early and slept in the street or in tents provided for women.

Loudspeakers played religious music across the city of some 6 million people.

Haider Farhan, 23, was finally beginning his trek from Sadr City to the shrine after spending most of Wednesday distributing food to pilgrims along the route.

"I am so tired, but I am determined to visit the shrine today," he said. "We are heading to the shrine in order to show our respect to the Imam al-Khadim and to our religion. We are expecting death any minute, but this will never deter us. God willing, all will be safe."

More than 1,800 Iraqi security forces were guarding the mosque complex, including 625 agents inside the shrine, officials said.

Shiite militiamen also were known to be deployed throughout the area.

U.S. troops took a lower-key security role, staying away from the mosque at the pilgrimage's heart to show respect, said the top U.S. ground commander in the area, Task Force Justice leader Lt. Col. Steve Miska.

The Iraqi military spokesman for Baghdad, Brig. Gen. Qassim al-Moussawi said security forces were on high alert, with helicopters on the lookout for mortar launching teams.

"The security measures are tight and there is a high coordination with the Multi-National forces and local committees and other ministries," al-Moussawi said in an interview outside the shrine with the Shiite Al-Forat TV station. "We can expect anything from the terrorists on this day."

Sunnis in Baghdad, meanwhile, expressed frustration over the three-day driving ban that began Wednesday as the Shiite-led government sought to protect the pilgrims from attacks.

"A number of sects live in Iraq, not only one and that three-day curfew is really too much for us," said Khalid Hussein Saleh, a 35-year old Sunni taxi driver in Baghdad's western Ghazaliyah neighborhood. "As a taxi driver, I earn my living on daily basis. How can I feed my family now?"

For the second day, Amer Mohammed Ali was unable to open his grocery store in Baghdad's western Shurta area because traffic was banned and he was unable to get supplies.

"This curfew has really confused citizens and delayed everything," the 45-year old Sunni said. "The government should have secured one or two roads for the pilgrims and not imposed such a curfew on all of Baghdad."