* Security forces fight militias in Basra * Sadr threatens national "civil revolt" * Fighting, curfews in southern towns (Updates throughout) By Aref Mohammed BASRA, Iraq, March 25 (Reuters) - Iraqi security forces battled Shi'ite militants in Basra on Tuesday in a drive to win control of the southern oil city, but violence and unrest spread to Baghdad and other cities. Police and health workers said at least 12 people were killed in the fighting in districts of central and northern Basra where Shi'ite cleric Moqtada al-Sadr's Mehdi Army has a strong presence. The commander of Iraqi forces in the operation said only that "many outlaws" had been killed. Sadr, an influential leader who has not been seen in public for months, issued a statement calling on Iraqis to stage sit-ins all over Iraq and said he would declare "civil revolt" if attacks by U.S. and Iraqi forces continued. The Iraqi government said the operation aimed to win control of Basra, whose vast oil fields provide most of Iraq's revenues, from militias and criminal gangs who dominate the semi-lawless city of about 2 million people. "This operation will not come to an end in Basra without the law prevailing and being respected," government spokesman Ali al-Dabbagh said after Prime Minister Nuri al-Maliki arrived in Basra to personally oversee the operation. The operation, which began at dawn and involved thousands of Iraqi troops, focused on Sadr's anti-U.S. Mehdi Army in northern and central Basra. By nightfall, many towns and cities across southern Iraq were under curfew as authorities sought to prevent further outbreaks of violence that threaten Iraq's fragile security. FURIOUS REACTION Clouds of black smoke rose above Basra and explosions and gunfire could be heard throughout the day. Reuters Television pictures showed gunmen firing mortars in the street, while others drove around in captured Iraqi army and police vehicles. "Bullets are coming from everywhere and we can hear the sound of rocket explosions. This has been going on since dawn," Basra resident Jamil told Reuters by telephone as he cowered in his home earlier in the day. The operation provoked a furious reaction by the Mehdi Army in Baghdad and in other cities in southern Iraq, with fighters taking to the streets and clashing with police. The militia has grown frustrated with a ceasefire imposed by Sadr last August. Sadrists say the truce has been abused by U.S. and Iraqi forces to make indiscriminate arrests ahead of provincial elections due in October, but the U.S. military says it only targets "rogue" members who have ignored the ceasefire. The U.S. military, which once called the Mehdi Army the greatest threat to peace in Iraq, says the seven-month-old ceasefire is one of the main factors contributing to a 60 percent drop in violence in Iraq since last June. GREEN ZONE ATTACKED Police sources said Sadr supporters seized control of five districts in the southern town of Kut after clashes between gunmen and police. Mehdi Army fighters also battled police in two neighbourhoods in the centre of the southern town of Hilla. In Baghdad, U.S. and Iraqi forces sealed off the Mehdi Army stronghold of Sadr City, a sprawling slum of 2 million people, after the militia ordered police and soldiers off the streets. Police said Mehdi Army fighters clashed with gunmen from the Badr Organisation, the armed wing of the rival Shi'ite Supreme Islamic Iraqi Council (SIIC). The Green Zone, the government and diplomatic compound in central Baghdad, was hit by several salvoes of rockets during the day. U.S. military spokesman Lieutenant-Colonel Steven Stover said they had been fired from Sadr City. Police later imposed curfews in the southern cities of Kut, Hilla, Nassiriya, Diwaniya and Samawa. Sadrists said a gradual "civil disobedience campaign" launched in several Baghdad districts on Monday would spread to other areas from Wednesday. As part of the campaign, pro-Sadr students forced Mustansiriya University in Baghdad to close on Tuesday. "The fact that Sadr called upon his followers to implement a civil disobedience campaign reflects the pressure building upon him. There is huge frustration among the group's rank and file," said Peter Harling, a Damascus-based analyst at the International Crisis Group think tank. (Writing by Ross Colvin, additional reporting by Waleed Ibrahim, Wisam Mohammed and Randy Fabi in Baghdad, editing by Sami Aboudi) For factbox on Basra, click on [nL25628385] For factbox on Mehdi Army, click on [nL25580219] For factbox on main players in Basra, click on [nL25341622]
Supporters of Shi'ite cleric Moqtada al-Sadr hold signs during a protest in Baghdad's Amil district March 25, 2008. Shi'ite cleric al-Sadr's Mehdi Army militia appeared in a show of force in ...
