The US provisional authority in Iraq has announced the existence of an arrest warrant for radical Shi'ite Muslim cleric Moqtada al-Sadr.
The warrant accuses Mr. al-Sadr and at least 30 accomplices, of the murder of a rival cleric, Abdel Majid al-Khoei last year in Najaf.
In Baghdad, US spokesman Dan Senor said the warrant was issued several months ago. He declined to say why it has not been announced earlier, but said an arrest will come with no advanced warning.
Moqtada al-Sadr, who has sought to establish a separate Shi'ite state in southern Iraq, is reported holed up in the main Shi'ite mosque in the central city of Kufa, surrounded by armed supporters.
Elsewhere in Baghdad, coalition forces fired on armed al-Sadr supporters, after insurgents opened fire on a U-S helicopter.
In Fallujah, hundreds of US and Iraqi troops closed all roads leading to the town. Western journalists reported explosions and gunfire coming from the center of the city. There were no immediate casualty reports.
Four American civilians were killed, burned and mutilated in Fallujah last week, and US military forces vowed a tough response to those killings.
News of the Sadr arrest warrant comes after clashes Sunday between the cleric's armed supporters and coalition forces killed nearly 60 people, including eight U-S troops. A spokesman for the firebrand cleric said Mr. al-Sadr welcomed the designation.
At least 28 Iraqis and eight American troops died Sunday in the Sadr City section of Baghdad. Another 22 people -- all but two of them Iraqis -- died in the holy city of Najaf, in the south, when a demonstration by Moqtada al-Sadr's supporters turned violent.
US military authorities say fighting broke out in Baghdad Sunday when coalition troops intervened to prevent Shi'ite militias from taking over police stations and other public buildings in the Sadr City neighborhood. In addition to the 35 deaths that were reported, hospital workers said more than 200 people were wounded.
Earlier Sunday, near the southern city of Najaf, at least 20 Iraqis, one American and a Salvadoran soldier died in an exchange of gunfire between troops and Shi'ite militiamen. Coalition forces said they were fired on from a crowd that had gathered for a protest demonstration, and they returned fire.