BAGHDAD, Iraq (CNN) -- Forty-two people were killed Thursday in Kut, southeast of Baghdad, Iraq's Interior Ministry said, the latest casualties in three days of clashes between militias and Iraqi security forces.
Fighters from the Mehdi Army militia take position Wednesday in clashes in the southern Iraqi city of Basra.
1 of 3 Iraq's offensive against what it characterizes as "outlaws" of hard-line Shiite cleric Muqtada al-Sadr's Mehdi Army militia began Tuesday in Basra, Iraq's second largest city.
Prime Minister Nuri al-Maliki, who has been overseeing the operation in southern Iraq, has given militants an ultimatum to surrender their weapons by Saturday.
The fighting, which also saw Baghdad's heavily fortified Green Zone -- home to the U.S. Embassy and the Iraqi government -- come under fire, has threatened to unravel a delicate al-Sadr cease-fire credited with reducing bloodshed between Sunnis and Shiites.
Since Tuesday, clashes in Basra and throughout Iraq's Shiite heartland have left more than 100 dead and many wounded in Basra, Baghdad, Hilla, Kut, Karbala and Diwaniya. Watch how militias send a message to al-Maliki »
Also Thursday, a U.S. government official was killed when militants fired rockets into the Green Zone, a spokesman for the U.S. Embassy in Baghdad said.
Casualty figures from Basra weren't available Thursday, but the number of deaths is expected to rise from the 40 to 50 that had been reported Wednesday.
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In Baghdad on Thursday, dozens of gunmen kidnapped the spokesman of the Baghdad security plan, Tahseen Sheikhly. Three of his guards were killed and his house burned in the attack, which an Interior Ministry official said was carried out by "outlaws," a reference to al-Sadr's militia.
Also Thursday, a car bomb explosion killed three people and wounded five others near a police patrol in central Baghdad, an Interior Ministry official said. There are no apparent links to the violence in the Shiite regions.
Witnesses in Basra report smoke rising and gunfire and explosions ringing out across the city, where Iraqi security forces, backed by U.S. and British troops, have been taking on fighters using grenades, mortar rounds and machine guns.
There was fighting Thursday in Jamhouriya, one of five neighborhoods the Mehdi Army controls, and Muqal, according to an official from Basra province and witnesses.
Speaking on a condition of anonymity, the provincial official said weapons such as machine guns and grenades were stolen from a military post in the Muqal area.
Al-Maliki briefed city and provincial officials Wednesday about the offensive and vowed to finish the job, even if it takes a month.
Provincial officials expressed reservations about the operation, saying Basra will fall into the hands of "outlaws" if al-Maliki fails to restore order.
Since the fighting started, Sadrists and government officials have spoken by phone in efforts to quell the violence, but no face-to-face talks have been scheduled. The Sadrists, who say security forces have unfairly targeted them in recent weeks, have been urging their followers to stage protests against the government. But so far, the cease-fire has not been rescinded.
Basra has been relatively quiet during the war, but the southern city has seethed with intra-Shiite tensions as Sadrists, the Islamic Supreme Council of Iraq and the Fadhila party have jockeyed for power. Learn more about the major players »
Much of the fighting in the Shiite heartland involves followers of al-Sadr and security forces aligned with the Islamic Supreme Council of Iraq's militia, the Badr Brigade.
The council dominates the ruling United Iraqi Alliance, but the Sadrist movement left the government last year after al-Maliki refused to demand a timeline for the withdrawal of American forces from Iraq. Both groups have strong contingents in the Iraqi parliament. Read how the conflict could doom Iraq's future
A provincial council official also said insurgents sabotaged an oil pipeline Thursday in Zubeir, a town near Basra. The attack sparked a large fire on the pipeline, which transfers crude oil to tanks in the city.
Meanwhile, the FBI identified the remains of two U.S. contractors who had been missing in Iraq for more than a year, a bureau spokesman said Thursday.
Minnesotan Paul Johnson-Reuben, 41, and Californian Joshua Munns, 25, were among four men kidnapped in November 2006 during an ambush in the southern Iraqi town of Safwan. All four worked for the Crescent Security Group, a Kuwaiti-based firm that escorts convoys.
The other two men -- Jonathon Cote, 25, and Bert Nussbaumer, 26 -- are still listed as missing. The FBI has the remains of one more body, which the bureau is trying to identify
What amazes me is that Al Sadr didn't stick to his guns and waited for Al Qaeda in Iraq to be almost a non-issue. He would have a better shot at coming out ahead if this would have happened a year ago. But then again I don't think he wants a political solution, he wants to go down in flames and attempt to get a civil war started. It's kind of the only chance he has left.
Of course, the Iraqi army won't get shit accomplished in this and the U.S. Army will come in and hammer these guys. That's my prediction anyway.