The Main Battle, The Najaf Showdown. Options

[Devastation]

BAGHDAD, Iraq (CNN) -- U.S. and Iraqi forces are preparing for a major assault in Najaf against fighters loyal to radical Shiite cleric Muqtada al-Sadr, the U.S. military said Wednesday.




More than 50 Iraqis were killed in the past day of battles between the U.S.-led multinational forces and al-Sadr's militia, according to an Iraqi Ministry of Health official.

Of the 57 killed, 29 died in the Meisan province in southeastern Iraq. Fourteen people were killed in Baghdad, and 10 died in Diwaniya province. Basra reported four deaths, according to the official, who added 323 Iraqis were wounded.

In Najaf, explosions and gunfire could be heard as military vehicles patrolled the streets and helicopter gunships darted across the skies.

On Tuesday, U.S. forces used loudspeakers to urge militants to surrender and residents to evacuate battle zones in the south-central city, which has an estimated population of about a half-million.

Iraqi forces and U.S. Marines have been pounding fighters loyal to al-Sadr over the past week. U.S. officials have accused al-Sadr of fomenting unrest. He is wanted by an Iraqi court in connection with the killing of a rival cleric last year.

A day after vowing to fight American troops to the death, al-Sadr issued a statement Tuesday saying he would welcome help from the United Nations in solving the crisis.

"I have no problem cooperating [with the United Nations]," the statement said. "We hope for this interference during these hard times to help us establish a world of peace and prosperity far away from wars and occupation."

Over the weekend, U.N. Secretary-General Kofi Annan said the world body was "ready to extend its facilitating role to the current crisis."

The 11th Marine Expeditionary Unit took over Monday as the lead multinational force in Najaf. Members of al-Sadr's Mehdi Army militia are holed up in the city's Imam Ali Shrine, one of the holiest sites in Shiite Islam.

Adnan al-Zurufi, governor of Najaf, gave permission Monday for military operations in the previously restricted area surrounding the shrine.

A senior U.S. commander said an estimated 2,000 militia fighters were in the shrine and in the Wadi Al Salam cemetery.

Najaf is about 80 miles (130 kilometers) south of Baghdad.