Residents of the normally calm, mainly Shi'ite town burned vehicles, including a police car, just outside the governor's office and demanded his resignation, the witnesses said.

Police in riot gear held up plastic shields as protesters hurled rocks. Armed police stood on the roof of the governorate.

Iraq's Shi'ite-led government took power in January polls promising to end guerrilla violence and restore public services.

But frustrations are running high in southern towns like Samawa, largely free of guerrilla violence but suffering from power and water shortages more than two years after a U.S.-led invasion toppled Saddam Hussein.

The Shi'ite south was ill-favoured under Saddam's Sunni-dominated rule and hopes were high after his overthrow by invading U.S. forces, and then the election of a Shi'ite-led government, that life would improve.

Daily life, however, remains hard for most and the Sunni insurgency further north continues to damage Iraq's economy.

Although majority Shi'ites are enjoying power for the first time, top Shi'ite groups are battling each other for power as the country moves towards national elections in December and rivalries have spread to their supporters in towns like Samawa.

The governor, Mohammed al-Hassaani, is backed by SCIRI, one of the Shi'ite political parties dominating the national government. Mohammed al-Zayadi, the head of the provincial council, is seen as a supporter of the Americans.

Fiery Shi'ite cleric Moqtada al-Sadr, who led two violent uprisings against U.S. troops, also has followers in the town, 270 km (168 miles) south of Baghdad.

The protests over poor water, electricity and sewage were called by the local council, which is dominated by Samawa's town elders, not Shi'ite parties. That suggests grassroots anger over what some say is widespread neglect by the new government.

Samawa residents made their economic desperation clear last month by taking to the streets and demanding jobs in the police force, a high-risk profession in a country where hundreds of policemen have been killed by suicide bombers or gunmen.

About 550 Japanese troops engaged in civil engineering projects are based in Samawa.

They are protected by nearby Australian combat troops since the Japanese government has promised voters that the controversial deployment will not involve combat.