Updated

Thousands of Shiite Muslims (search) marched peacefully through the capital Monday to protest the American occupation of Iraq and reject what they feared would be a U.S.-installed puppet government.

Small groups of U.S. infantrymen, including snipers on nearby rooftops, watched the rally but did not intervene. Several dozen Shiite organizers armed with AK-47 assault rifles patrolled the area. They, too, were left alone by the Americans.

Up to 10,000 people gathered in front of a Sunni Muslim (search) mosque in Baghdad's northern district of Azimiyah, then marched across a bridge on the Tigris River to the nearby Kadhamiya quarter, home to one of the holiest Shiite shrines in Iraq.

It appeared to be the largest protest against the U.S. occupation since the war ended.

"What we are calling for is an interim government that represents all segments of Iraqi society," said Ali Salman, an activist.

Some carried portraits of the late Ayatollah Ruhollah Khomeini of Iran (search), senior Iraqi Shiite clerics and of Imam Hussein, one of the most revered Shiite saints.

"We decided to gather outside a Sunni mosque to show unity between Shiites and Sunnis," said Rashid Hamdan, an organizer.

He said the procession was organized mainly by religious groups from Baghdad's al-Thawra suburb -- formerly known as Saddam City, home to an estimated 2 million Shiites.

Shiites make up the majority of Iraq's 24 million people but were long excluded from political power by Saddam Hussein's Sunni Muslim regime.

For decades, Shiites were banned from publicly practicing some of their rituals, and many of their top clerics and activists were murdered, jailed or pushed into exile under Saddam's 23-year rule.

Many of Monday's protesters carried portraits of Imam Mohammed Sadiq al-Sadr, a top Shiite cleric slain in the Shiite holy city of Najaf in 1999. His death is widely blamed on Saddam's agents.

Since Saddam's ouster by coalition troops last month, there has been a spate of smaller gatherings, some of them hundreds strong, demanding that occupying forces withdrawal. Monday's march was the biggest in terms of numbers and had a distinctly political message.

The crowd chanted "No Shiites and no Sunnis, just Islamic unity," sang religious songs, and carried banners reading "No to the foreign administration," and "We want honest Iraqis, not their thieves."

That appeared to be a reference to Ahmad Chalabi (search), head of the Iraqi National Congress and one of the key players in current rounds of U.S.-led discussions to form an interim government. He was convicted in 1992 by a Jordanian court of embezzlement and fraud, and some Iraqis have criticized him harshly. Chalabi says he was set up.

The noisy but peaceful protest appeared to be well-organized. Organizers sprayed participants with water to cool them off and formed human chains around the crowd to ensure that the marchers stayed in line and no violence occurred.

At one point, the crowd swelled to about 10,000 people, but many participants soon wandered off, and were replaced by fresh batches of demonstrators. At the end of the march, about 5,000 gathered near the shrine of Musa sl-Kazim, a much revered 9th-century Shiite saint.

Some banners held aloft by protesters called on al-Hawza al-Ilmiyah, the highest religious Shiite authority based in Najaf, to form an interim government.