U.S. tanks pushed into Najaf's vast cemetery-turned-battlefield Tuesday as helicopter gunships fired on Shiite militiamen hiding there. American patrols with loudspeakers went through the city, warning militants to leave or face death.
Explosions shook the streets and black smoke rose over parts of Najaf, but the fighting with Shiite cleric Muqtada al-Sadr's Mahdi Army militia appeared more sporadic than in recent days.
A large fire broke out at a hotel about 300 yards from the Imam Ali Shrine, Najaf's holiest site, which fighters have reportedly been using as a base. Witnesses said insurgents were firing from inside the hotel and U.S. forces returned fire.
In a new tactic, U.S. military vehicles equipped with loudspeakers drove through the streets warning residents to stay away from the fighting and for militants to put down their weapons and leave. "We ask residents to cooperate with the Iraqi army and police," a voice said in Arabic. "There will be no truce or negotiations with terrorists."
In other recent developments:
Small clashes also broke out in the Baghdad Shiite neighborhood of Sadr City, despite a nighttime curfew imposed Monday.
Mahdi Army militants repeatedly attacked a district council hall, clashing with U.S. and Iraqi forces protecting the building, said U.S. Capt. Brian O'Malley of the 1st Brigade Combat Team. Groups of three to five fighters have been attacking the building with mortars, gunfire and rocket-propelled grenades "every hour or so" from 7 a.m. to about 5 p.m., he said.
The fighting killed one person and wounded 18, Health Ministry officials said.
There were no employees there during the attacks, and O'Malley said about 14,000 people "haven't been able to go to work since the fighting started" in Sadr City days ago.
While U.S. and Iraqi forces were trying to quell the eruption of Shiite violence, attacks by Sunni Muslim militants persisted.
A roadside bomb detonated as a U.S. military vehicle drove on a street in central Baghdad on Tuesday, slightly wounding two soldiers, the military said. On Monday a suicide car bomb targeting a deputy governor killed six people, and a roadside bomb hit a bus, killing four passengers.
Another insurgent group warned in a videotaped message it would launch a campaign of attacks on government offices in Baghdad starting Tuesday, telling employees to stay away.
The sixth day of Shiite violence came after al-Sadr said Monday that he would fight "until the last drop of my blood has been spilled."
Clashes intensified around the southern city of Basra, where a British soldier was killed and several others wounded in fighting with militia near al-Sadr's office Monday, the British Ministry of Defense said. Three militants were killed and more than 10 were wounded, Iraqi police said.
Much of the fighting in Najaf remained centered on the vast cemetery near the Imam Ali Shrine. The U.S. military said Mahdi Army gunmen were launching attacks from the cemetery and then running to take refuge in the shrine compound, one of the holiest sites in Shia Islam.
Najaf Gov. Adnan al-Zarfi gave U.S. forces approval to enter the shrine, a senior U.S. military official said Monday. "We have elected at this point not to conduct operations there, although we are prepared to do so at a moment's notice," the official said.
Such an offensive would almost certainly cause widespread outrage among the nation's Shiite majority and further exacerbate the crisis.
The military official estimated that 360 insurgents were killed between Thursday, when fighting began, and Sunday night, a figure the militants dispute. Five U.S. troops have been killed in the fighting. About 20 police also have been killed, Najaf police chief Brig. Ghalib al-Jazaari said.
The fighting has shattered a series of delicate truces worked out two months ago that ended the Mahdi Army's first uprising, which broke out in April. During that period, U.S. commanders vowed to "capture or kill" al-Sadr, but later tacitly agreed to let Iraqi authorities deal with the cleric.
U.S. forces were apparently continuing the hands-off policy toward al-Sadr. The senior U.S. military officer in Baghdad, speaking on condition of anonymity, said the cleric "is not an objective; we are not actively pursuing him."
But the fighting has complicated the security situation for Prime Minister Ayad Allawi's government as it tried to take a tough stance against the mainly Sunni campaign of attacks, bombings and shootings plaguing Iraq for the past 15 months.