During this week's uprising, Iraqi police (search) have abandoned stations or stood by while gunmen roamed the streets, raising concerns about their role in a future Iraq.

In the southern city of Najaf (search), a policeman watched helplessly on Thursday as a pickup truck carrying a dozen heavily armed Shiite militiamen went past his police station -- already in the militia's hands.

"Look, how can we control such a situation?" he told an Associated Press reporter.

The policeman, who refused to give his name, said that if a cleric issues a religious ruling calling for it, "I will immediately leave the police service. ... We came to serve this city, but now we have become targets."

In many cities, the unexpected strength of a Shiite Muslim militia known as the al-Mahdi Army (search) -- now in full or partial control of at least three cities in the south -- has cowed the police force that U.S. administrators are counting on to maintain security in the future Iraq.

The Iraqi interior minister, who is in charge of police, resigned Thursday and complained of the divided loyalties among the nationwide force of 75,000.

"The coalition appoints policemen, clerics appoint policemen, as do political parties and militias. The same thing with promotions. All these things led to a lack of security," Nuri al-Badran told journalists in Baghdad (search).

Iraq's police force was started from scratch by the U.S.-led coalition after the overthrow of Saddam Hussein's regime, but a lack of resources and unity means it remains largely ineffective in the face of better-armed gunmen.

Policemen across the country complain that they don't enjoy the trust of the Americans and that local communities view them with suspicion. In some provincial towns, they're also reluctant to do battle with relatives or fellow tribesmen.

In Sadr City (search), a Baghdad neighborhood that's home to almost 2 million Shiites, policemen abandoned three stations to regroup in a fourth during clashes between U.S. forces and followers of radical Shiite cleric Muqtada al-Sadr.

Maj. Gen. Martin Dempsey, the U.S. commander responsible for security in Baghdad, gave a mixed assessment of the police performance during Sunday's battle, in which he lost eight soldiers.

Some officers showed bravery and fought alongside the Americans, while others chose to stand aside, he said.

In Falljuah (search) -- where Marines are battling Sunni insurgents -- police were conducting operations with U.S. forces, said Gen. Richard B. Myers (search), chairman of the Joint Chiefs of Staff. But, he said, "There are other instances where Iraqi forces have not been as aggressive."

In Sadr City, three police officers led by a colonel sat alongside clerics at a reviewing stand while thousands of militiamen filed past in a parade on Saturday.

Al-Sadr makes no effort to conceal the cooperation between his militiamen and the police in Najaf, where he is based.

"I would like to thank my honest brothers in the Iraqi police who are cooperating with the Iraqi people," he said in a statement Thursday. "This ordeal has shown that all the Iraqi people are united."

Police appeared to have more control farther south in the towns of Nasiriyah (search) and Amarah, where al-Sadr followers have battled Italian and British troops. Residents said an understanding was reached between Shiite clerics loyal to al-Sadr and the Italians in Nasiriyah.

In the two towns, police patrolled the streets normally. Clusters of al-Sadr militiamen were also out in public, but unarmed.

In Basra, police agreed Thursday to continue to maintain security provided that British troops stay out of the heart of the city, according to police chief Brig. Mohammed Kadhem al-Ali.

U.S. Defense Secretary Donald Rumsfeld said American troops need to step up training of Iraqis, but added the number of Iraqi police deaths shows the local forces are pulling their weight.

"I believe that since Sept. 1, according to the reporting we have, more Iraqi security forces have been killed than coalition forces, which suggests that the Iraqi security forces are engaged and doing things, and not sitting back in their barracks," he said Wednesday.

But some Iraqis aren't so sure.

In the mainly Sunni neighborhood of al-Azamiyah in Baghdad, police abandoned their station Monday night when a band of local gunmen joined by al-Sadr militiamen from an area across the Tigris river advanced on the building.

"The police just left," said Qusai Abdel-Sattar, a retired accountant who lives in al-Azamiyah. "They did not want a fight."