BAGHDAD &

The powerful Shiite cleric Muqtada al-Sadr publicly ordered his huge militia Wednesday to "freeze" operations for up to six months, but U.S. and Iraqi officials expressed skepticism of the cleric's intentions and his ability to control the fractured network of fighters who kill in his name.

Al-Sadr issued his order following a day of Shiite-against-Shiite gunfire that killed 49 people during a religious ceremony in the holy city of Karbala. In a statement, he said the freeze would apply to his Mahdi Army militia "without exception in order to have it restructured in a way that would retain for this ideological body its prestige."

Some officials interpreted the statement to mean al-Sadr had called off attacks on American soldiers as well as Iraqi opponents, but a source close to al-Sadr said some fighting would continue in the name of "self-defense."

"This does not cover all military activities because there are violations being done by the occupation forces every now and then and we expect that these violations will continue in the future, and in these cases the Mahdi Army members will defend themselves," said the source, who spoke from al-Sadr's headquarters in the southern city of Najaf. "This decision was made in effect to calm things down, especially in Karbala."

Tuesday's street fighting took place as hundreds of thousands of Shiite pilgrims milled around Karbala during a festival marking the birthday of a 9th-century Shiite imam.

official accounts, the fighting pitted government security forces against unidentified gunmen. But many people in Karbala described it as a battle between the two main Shiite militias vying for power in southern Iraq, the Mahdi Army and the Badr Organization, the armed wing of the Supreme Islamic Iraqi Council.

Officials from both groups condemned the bloodshed and denied that their fighters took part.

Hadi al-Amiri, leader of the Badr Organization, said that neither the Karbala governor, police chief, nor shrine guards involved in the fighting are members of his organization. He and al-Sadr aides said that outlaw fighters who claim to be members of the Mahdi Army mounted the attacks.

"These undercover Baathists were trying to create strife and draw the matter into a Shiite-versus-Shiite battle between the Sadr followers and the Supreme Islamic Iraqi Council," al-Amiri said in an interview.

The government evacuated thousands of people from Karbala, as Prime Minister Nouri al-Maliki declared an indefinite curfew in the city following the violence. Touring the city, home to two shrines central to the beliefs of Shiite Muslims, al-Maliki declared that order had been restored.

But retaliatory violence broke out at Supreme Islamic Iraqi Council offices in Baghdad and several southern cities, some of which were burned and ransacked. Six Badr members died in the fighting and four others were injured, al-Amiri said.

The legions of Shiite men who claim to be members of the Mahdi Army are described by Iraqi and U.S. officials as a relentless force in killing and displacing Sunnis, running extortion schemes and expanding Shiite dominance in Baghdad. Al-Sadr's organization has also opened dozens of offices to provide social services to Shiites.

But U.S. and Iraqi officials also depict the organization as weakened by the recent arrests of several mid-level commanders, by al-Sadr's frequent absences in Iran, and by the departure of the party's Cabinet ministers and parliament members from the government.

"As far as Sadr, I wouldn't put too much stock into what he says," said a U.S. military official in Baghdad, speaking on condition of anonymity. "He's been spending most of his time in Iran and because of that, probably has little control over some of the more militant factions" of the Mahdi Army. "As the leadership has been picked off, so has his influence," the official said.

In places where the Mahdi Army is strong, such as the Shiite enclave of Kadhimiyah in Baghdad, officials said, it is doubtful that profit-motivated criminal gangs that operate under al-Sadr's banner would change their behavior.

Many groups claiming to be part of the Mahdi Army do not respond to commands from the group's central base in Najaf, according to Lt. Col. Steven Miska, a deputy brigade commander based in Kadhimiyah. He suggested that al-Sadr's statement could be "a political ruse" by which the militia would say publicly it had shut down but continue operations.

U.S. commanders in recent weeks have attributed much of the violence to Iranian-influenced "rogue" militiamen who have split off from al-Sadr and are pursuing their own ends.

The source close to al-Sadr agreed that there are "some groups from inside Iraq that have infiltrated the Mahdi Army and are now working for the benefit of the foreign agenda."

"So this decision and the six-month period will be a good chance to clean the Mahdi Army of those groups that have infiltrated, and reorganize it on a sound basis," the official said.

As pilgrims returned from Karbala to Baghdad Wednesday, the capital's streets were choked with a procession of vans and trucks. Men waved AK-47 rifles from passing vehicles and people chanted insults at the leader of the Supreme Islamic Iraqi Council, Abdul Aziz al-Hakim.

"The whole atmosphere is tense right now, because of the situation in Karbala yesterday was so unstable," said Brig. Gen. Falah Hassan, a brigade commander in Kadhimiyah. "The coming days will reveal whether they will follow the orders of Muqtada al-Sadr or will act on their own." (begin optional trim)

The rival movements of al-Sadr and Hakim, both heirs to powerful political dynasties, have competed for Shiite supremacy for generations. Among American officials, Hakim has a reputation as a more moderate voice of the establishment while al-Sadr is a rebel firebrand and inspiration for the impoverished masses. His men have fought fierce battles against the U.S. military during the war.

Hakim has pushed for the creation of a semiautonomous Shiite region in the south while al-Sadr expresses nationalist sympathies of keeping Iraq strongly united; one of his main power bases is in eastern Baghdad. The violence in Karbala, if it was indeed an open battle between these groups, would be an escalation but not mark a major change in sentiments.

"This probably won't be the start of any sort of sea change with regards to militias," said the U.S. military official. The rival groups "have been duking it out for years, especially down south, and they will continue to as well." (end optional trim)

Meanwhile in Baghdad, eight Iranians making a state-sponsored visit to Iraq were released Wednesday by the U.S. military after being detained at their Baghdad hotel Tuesday night, the military said.

Staff writer Megan Greenwell and special correspondents Naseer Nouri, Saad al-Izzi, and K.I. Ibrahim contributed to this report.