Militias backing a wanted radical Shi'ite cleric waged a fierce battle against British forces in the southern Iraqi city of Basra Saturday.

The attack came a day after an aide to Shi'ite cleric, Moqtada al-Sadr, offered cash for capturing or killing coalition soldiers. The gunmen attacked British patrols and government buildings in the southern Iraqi city of Basra.

An aide to the radical religious leader, Sheikh Abdul-Sattar al-Bahadli, on Friday offered cash rewards for capturing or killing coalition forces. He also said anyone who captured female soldiers could keep them as slaves.

Meanwhile in Baghdad, AFP reported several hundred Iraqis gathered Saturday for a conference aimed at drafting a proposal to end the occupation of Iraq. The participants included Arab nationalists and moderate Sunni and Shi'ite Muslims. The one-day conference did not include members of the U.S. appointed Iraqi Governing Council.

In Basra, members of the cleric's Mehdi army opened fire on British patrols, assaulted the governor's offices and fired rocket-propelled grenades at the coalition headquarters.

British troops responded by surrounding Moqtada al-Sadr's headquarters in Basra and retook control of the governor's building. The cleric is wanted by U.S. authorities for the killing last year of a rival pro-U.S. cleric.

The Mehdi army controls the holy cities of Najaf, Karbala and Kufa all located south of Baghdad, and over the past several days, has been involved in numerous clashes with coalition forces. Coalition military officials said 20 militiamen had been killed Friday in the cities of Najaf and Karbala.