BAGHDAD - Tens of thousands of Shiites - a sea of women in black abayas and men waving Iraqi flags - rallied Monday to demand that US forces leave their country. Some ripped apart American flags and tromped across a Stars and Stripes rug.

Demonstrators wave Iraqi flags as they march during a rally marking four years to the day since Baghdad fell to invading American troops, in Najaf, south of Baghdad, April 9, 2007. [AP]

The protesters marched about three miles between the holy cities of Kufa and Najaf to mark the fourth anniversary of the fall of Baghdad. In the capital, streets were silent and empty under a hastily imposed 24-hour driving ban.

Radical Shiite cleric Muqtada al-Sadr ordered up the march as a show of strength not only to Washington but to Iraq's establishment Shiite ayatollahs as well.

Al-Sadr, who disappointed followers hoping he might appear after months in seclusion, has pounded his anti-American theme in a series of written statements. The most recent came on Sunday, when he called on his Mahdi Army militia to redouble efforts to expel American forces and for the police and army to join the struggle against "your archenemy."

The fiery cleric owes much of his large following to the high esteem in which Shiites hold his father, Ayatollah Mohammed Sadiq al-Sadr, who was assassinated in 1999 by suspected agents of Saddam Hussein. Al-Sadr dropped from view before the start of the latest Baghdad security operation on Feb. 14. US officials say he is holed up in Iran. His followers insist he's returned to Najaf.

Fearing suicide attacks, car bombings or other mayhem in the capital, Iraq's generals ordered all vehicles off the streets for 24 hours starting at 5 a.m. Monday, normally a work day. The capital was eerily quiet, shops were shuttered and locked and reports of sectarian violence fell to near zero.

Police and morgue officials reported finding just seven bodies dumped in the capital, only the second time the number of sectarian assassination and torture victims had dipped that low in the course of the Baghdad security operation. A total of 25 people were killed or found dead in the country Monday, according to police and morgue reports.

A double line of police cordoned the marchers' route from Kufa to Najaf, sister cities on the west bank of the Euphrates River. The holy places, 100 miles south of Baghdad, are a prime destination for Shiite pilgrims.

Among the snapping flags and giant banners, leaflets fluttered to earth, exhorting the marchers in chants of "Yes, Yes to Iraq" and "Yes, Yes to Muqtada. Occupiers should leave Iraq."

Salah al-Obaydi, a senior official in al-Sadr's Najaf organization, called the rally a "call for liberation. We're hoping that by next year's anniversary, we will be an independent and liberated Iraq with full sovereignty."

And the head of al-Sadr's parliamentary bloc, Nassar al-Rubaie, blasted the US presence as an affront to "the dignity of the Iraqi people. After four years of occupation, we have hundreds of thousands of people dead and wounded."

A key Washington official saw it differently.

"Iraq, four years on, is now a place where people can freely gather and express their opinions," Gordon Johndroe, the National Security Council spokesman, said aboard Air Force One. "And while we have much more progress ahead of us - the United States, the coalition and Iraqis have much more to do - this is a country that has come a long way from the tyranny of Saddam Hussein."

Col. Steven Boylan, a US military spokesman and aide to Gen. David Petraeus, the US commander in Iraq, praised the peaceful demonstration and said Iraqis "could not have done this four years ago."

Iraqi soldiers in uniform joined the crowd of marchers which stretch for at least three miles and was led by a dozen turbaned clerics, a Sunni Muslim among them. Many marchers, especially youngsters, danced as they moved through the streets, littered with balloons.

Brig. Abdul Kerim al-Mayahi, the Najaf police chief, said there were as many as 600,000 in the march, although other estimates were significantly lower. He said 30 lawmakers made the hike and there was no American troop presence except surveillance from helicopters hovering above.

Monday's demonstration marks four years since US Marines and the Army's 3rd Infantry Division swept into the Iraqi capital 20 days into the American invasion.

Foreign Minister Hoshyar Zebari noted that "mistakes were made" after Saddam was ousted, pointing to decisions made by the first US governor of Iraq, L. Paul Bremer.

"The main mistake was a vacuum left in the fields of security and politics, and the second mistake was how liberating forces became occupation forces," Zebari told Al-Arabiyah television.

Cars were banned from Najaf for 24 hours starting from 8 p.m. Sunday, and buses idled at all city entry points to transport arriving demonstrators or other visitors.

While al-Sadr had ordered his militia to disarm and stay off the streets during the Baghdad crackdown, he has notched up his anti-American rhetoric in three brief but hostile statements demanding the departure of US troops.

"You, the Iraqi army and police forces, don't walk alongside the occupiers, because they are your archenemy," he wrote, apparently referring to three days of clashes between his Mahdi Army militiamen and US-backed Iraqi troops in Diwaniyah, 80 miles south of Baghdad.

A US soldier was killed there Sunday, according to Col. Michael Garrett, with the US Army's 25th Infantry Division. He spoke to reporters in Diwaniyah as American troops continued operations.

On Monday night, police officials in Diwaniyah said the toll since the start of the operation Friday was 14 dead and 47 wounded, both figures including civilians and members of the Mahdi Army. The numbers could not be independently confirmed.