A bomb exploded Wednesday in a crowd of day laborers in central Baghdad, killing eight people and wounding 28, police said. Dozens of gunmen attacked the provincial offices in Basra, apparently to avenge a tribal leader killed the day before.

All eight people killed in the Baghdad bombing were civilians, though four police were among the wounded, said police Lt. Bilal Ali said.

The attack in Basra was carried out by members of the Bani Assad tribe, whose leader was assassinated Tuesday in the southern city. The tribesmen believed senior provincial officials were behind the killing and laid siege to the government headquarters, according to an official trapped in the besieged building.

In Mosul, 225 miles northwest of Baghdad, armed clashes erupted between police and assailants in three predominantly Sunni Arab neighborhoods, police Lt. Col. Abdul-Karim Ahmed Khalaf said.

At least five gunmen were killed and six were arrested, he said. Western Mosul is predominantly Sunni Arab, while Kurds dominate in the east of the city.

The clashes occurred one day after a suicide car bomber killed nine people in an attack on the Mosul headquarters of the Patriotic Union of Kurdistan, a Kurdish party headed by President Jalal Talabani.

Much attention has been focused on the security crisis in Baghdad following a wave of sectarian killings. But the unrest in such widely scattered parts of Iraq indicates the precarious state of security elsewhere in this country and the challenge facing U.S. and Iraqi forces in trying to restore order.

The Iraqi army general command said order had been restored in the Shiite holy city of Karbala following street battles the day before between security forces and followers of anti-American cleric Mahmoud al-Hassani, which left 12 dead, including two Iraqi soldiers.

The clashes erupted after police raided the cleric’s office, ostensibly to look for weapons. Gangs of al-Hassani’s followers roamed the streets Tuesday, firing Kalashnikovs, machine guns and rocket propelled grenades at police and army patrols.

Security forces rounded up 281 people in the wake of the clashes, the army statement said.

Elsewhere, however, hundreds of al-Hassani’s followers gathered in Shiite towns in the area and threatened to march on Karbala in support of their colleagues there, police said.

Al-Hassani gained prominence for his nationalistic stand, calling for an Iraq free of influence from the Americans and Shiite-dominated Iran. Other key Shiite figures have sought to dampen his influence, which is mostly in Karbala and Basra, Iraq’s second-largest city.

In Baghdad, meanwhile, assailants blew up a monument erected to 18 Shiite children who were killed in July 2005 suicide bombing in the city. One American soldier was also killed as he was distributing candy to the children.

Sectarian unrest in the Baghdad area has prompted the U.S. command to order 12,000 U.S. and Iraqi reinforcements into the streets of the capital. U.S. Ambassador Zalmay Khalilzad has described sectarian violence in Baghdad as the greatest threat to Iraq’s future.

However, many other parts of the country remain unstable after three years of the U.S.-led international military presence, including the Sunni insurgent stronghold of Anbar and Basra, where British forces have failed to prevent Shiite militias from infiltrating the police and security services.

In Kut, 100 miles southeast of Baghdad, authorities found three bodies floating in the Tigris River. All were bound, blindfolded and showed signs of torture, morgue official Maamoun al-Ajili said.

Copyright © 2006 The Associated Press