In the biggest anti-U.S. demonstration since the end of the war, thousands of Shiite Muslims marched peacefully through the capital on Monday to protest the U.S. occupation and reject what they feared would be a U.S.-installed puppet government. Up to 10,000 rallied in front of a Sunni Muslim mosque in the capital's northern district of Athamiyah, then marched to the nearby Kadhamiya quarter, home to one of the holiest Shiite shrines in Iraq. Some carried portraits of the late Khomeini of Iran and other noted Shiite clerics. "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 by religious groups from Baghdad's al-Thawra suburb - formerly known as Saddam City, where an estimated 2 million Shiites live. Since Saddam Hussein's ouster last month, there has been a spate of smaller gatherings, some of them hundreds strong, demanding the occupying forces' withdrawal. But Monday's march was the biggest in terms of numbers. 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, head of the Iraqi National Congress and one of the key players in current round of U.S.-led discussions to form a new government. He was convicted in 1992 by a Jordanian court of embezzlement and fraud, and some Iraqis have criticized him harshly. Of course 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 monitors followed the crowd to ensure that no violence occurred. "What we are calling for is an interim government that represents all segments of Iraqi society," said Ali Salman, an activist. ** US Iraq Chief Arrives in Mosul*** US administrator for Iraq Paul Bremer arrived in this northern city after announcing a host of political and law-enforcement measures in a frenzied first week on the job, as a top UN official focused on the plight of Iraqi children. In Mosul, Bremer sought to press his campaign to stem post-war lawlessness in Iraq by touring a police station and a courthouse in Iraq's main northern city. Bremer also held talks with Mayor Ghanim al-Basso and other members of a new multi-ethnic city council installed on May 5 in a bid to stem unrest in the often-volatile, ethnic quilt of a city. Residents here include Arabs, Kurds, Turkmen and Assyrian Christians. The visit caps Bremer's first week as Iraq's top US overseer, during which he banned Saddam's Baath party chiefs from the public sector, sought to boost security, and hinted that the US-led coalition would extend its grip on power in the country. But in an illustration of dangers facing US troops in Iraq, three US soldiers were killed and six injured as US-led forces stepped up patrols in an attempt to bring order, the US Central Command announced Sunday. **PHOTO CAPTION*** Paul Bremer (L), the new US overseer in Iraq, listens to US commander on arrival at Mosul airport in northern Iraq. (AFP/Roberto Schmidt)