BAGHDAD -- Clashes erupted yesterday between followers of a radical Shi'ite cleric and his opponents in the holy city of Najaf, leaving at least six dead and scores injured during a violent day throughout Iraq ahead of a National Assembly vote on a new constitution.
In the capital, as many as 40 gunmen and suicide bombers staged a brazen daylight attack on police that left at least 15 dead and 56 injured.
Insurgents launched three attacks in and around the city of Baqubah that left at least eight Iraqis dead, and raided the home of a police commando in Samarra, publicly executing one of his relatives before blowing up the house.
The violence occurred as sectarian and political tensions simmered on the eve of today's vote in the transitional National Assembly on the draft constitution. Although the document is believed to have the support of a majority of the legislators, its call for a degree of federalism and other provisions have drawn strong opposition from some Iraqis.
A US military official in Baghdad, speaking yesterday on condition of anonymity, said he anticipated more violence today as the assembly meets.
''We believe that the enemy is continuing to try to influence the drafting of the constitution and is still intending to conduct some larger scale operation in Baghdad and elsewhere associated with the release," he told reporters.
Police closed off roads and imposed a curfew on Najaf, a shrine city that has been quiet since clashes between US troops and members of the Mahdi Army, a militia loyal to radical cleric Moqtada al-Sadr, who has been critical of the new constitution.
Sadr's followers charged that they were victims of an unprovoked attack by rioters who tried to burn down the cleric's Najaf office. Witnesses said demonstrators were protesting an increase in political activity in and around the old city, which many Najaf residents and clergy consider holy.
Sadr's followers blamed a rival Shi'ite faction for the clashes and announced they would pull their bloc of at least 20 lawmakers and three ministers out of government. They said they have mobilized their militia, whose gun battles with US troops a year ago traumatized the nation.
Sadr supporters are hungry for revenge against the Supreme Council of the Islamic Republic of Iraq, the rival political party of Abdelaziz Hakim, which controls the Interior Ministry, said Fatah Sheik, a leader of Sadr's parliamentary bloc.
Shopkeepers and bystanders were among those killed and injured during the assault on police in the Jamiyaa neighborhood of Baghdad. The attackers, believed to be Sunni Arab insurgents, were armed with car bombs, rockets, and machine guns, police said.
The apparent target, a visiting police chief from the city of Samarra, survived. Iraqi police and soldiers, as well as US forces, rushed into the area to head off further attacks. Most of the gunmen escaped, but two suspects carrying rocket-propelled grenade launchers were arrested, a police official said.
Also in the capital, Iraq's deputy justice minister Osho Ibrahim narrowly escaped an assassination attempt, the second directed at him in two days.