Reports from Baghdad say U.S. forces have launched a helicopter strike against militiamen who follow a Shi'ite cleric branded as an outlaw by the U.S. administrator in Iraq. Fighting between coalition forces and the Shiite militias has killed nearly 80 people since Sunday.

Witnesses said Apache helicopters opened fire on the private militias of radical Shi'ite cleric Moqtada al-Sadr, a day after deadly fighting broke out between rioting Shi'ite demonstrators and coalition forces. The new clashes erupted after supporters of the Shiite cleric seized control of at least one government building. On Sunday, the outspoken critic of the U.S. occupation of Iraq called for his followers to stop demonstrating and terrorize the enemy.

The U.S. administrator in Iraq, Paul Bremer, branded the cleric an outlaw and said that his call for violence was going too far. "He has called for attacks on Iraqi forces and on the coalition," Mr. Bremer said.

A supporter of Moqtada al-Sadr read a response by the 30-year-old cleric at a mosque near Najaf, which said he was proud to be an outlaw because it means, in his words, breaking the law of the American tyranny.

Meanwhile, Shi'ite demonstrations continued in the southern Iraqi city of Basra. Protesters are calling for the release of a top al-Sadr aide, who was arrested Saturday in connection with the killing of a rival Shiite cleric last year.

Meanwhile, U.S. troops surrounded the city of Fallujah, a Sunni Muslim stronghold where four American civilian contractors were killed and their bodies mutilated by jubilant mobs last week. An official with the U.S. Marines said American and Iraqi forces are poised to launch what he called an extended operation, code-named Operation Vigilant Resolve, but declined to disclose further details.