BAGHDAD Ñ The U.S. military offensive against the Iranian-backed Mahdi Army has been hampered by feuding within the Iraqi government leadership.

Iraqi government sources said the U.S.-led military coalition has been inundated with contradictory messages from a range of leading Iraqi politicians. The sources said that much of the Iraqi Cabinet appears to oppose the U.S. attack on the Mahdi Army in Najaf as military forces come within 200 meters of the insurgency stronghold.

"We are deeply concerned about the viciousness of the U.S. military's assault on Najaf," said Jawad Maliki, a senior official in the Shi'ite Dawa Party led by Iraqi Vice President Ibrahim Jaffari. "What is happening in Najaf could open the door to a serious crisis that would undermine the whole political process in the country."

On Friday, Iraqi sources said Mahdi Army commander Moqtada Sadr was injured or killed in the Imam Ali mosque in Najaf, Middle East Newsline reported. The sources said Sadr was injured in a U.S. artillery strike, an assertion confirmed by the Mahdi Army. Sadr, the sources said, was negotiating with the Iraqi government for his safe passage out of Najaf.

Earlier, U.S. 11th Marine Expeditionary Force, backed by main battle tanks and AH-64 Apache helicopters, launched a strike on a Najaf cemetery described as the last stronghold of the Mahdi Army. About 500 people have been killed in the week-long battle with Shi'ite insurgents loyal to Sadr.

"Today's operations are designed to restrict freedom of movement of Sadr forces in Kufa and Najaf and to further isolate them in these mosques, which they use as a base of operations," U.S. Army Brig. Gen. Erv Lessel, the multinational force's deputy operations director, said on Thursday. "Militia use of these shrines as protective shields could lead to damage of these sacred sites."

Iraqi sources said the coalition has been consulting with Prime Minister Iyad Alawi, who has approved the offensive in Najaf. But they said Alawi has been opposed by a range of politicians led by President Ghazi Al Yawar.

"The biggest fear is that of a prolonged operation that will end up destroying Najaf and the holy sites," a government source said.

U.S. commanders said the operations in Kufa and Najaf have spared Shi'ite shrines. They said coalition troops have not attacked either the Imam Ali Mosque in Najaf nor the Kufa Mosque, despite their use by the Mahdi Army.

A statement by the coalition said police headquarters in Najaf came under mortar fire from Mahdi Army units stationed in the Imam Ali Mosque.

The statement said Sadr's militia fired 25 mortar rounds from within the walls of the mosque.

Alawi has also authorized the deployment of thousands of police, army and security forces for Kufa and Najaf operations. The commanders said some of the Iraqi forces have been performing well and repelled three Mahdi Army attacks in the center of Najaf.

"The Iraqi police and the Iraqi armed forces will be the forces to liberate these locations that have been occupied by these gangs," Iraqi State Minister Kasim Daoud said.