Firebrand Shiite Muslim cleric Muqtada al-Sadr announced Wednesday he's temporarily suspending the activities of his feared Mahdi Army militia...

BAGHDAD — Firebrand Shiite Muslim cleric Muqtada al-Sadr announced Wednesday he’s temporarily suspending the activities of his feared Mahdi Army militia so the organization can be restructured.

The announcement, a day after Mahdi Army members were accused of inciting clashes in Karbala that killed at least 52 people, seemed to be a startling admission that the militia, which twice fought brutal uprisings against U.S. troops and has been blamed for thousands of death-squad killings, was no longer under al-Sadr’s control.

If the Mahdi Army stands down, that could ease what U.S. officials have said is their greatest long-term worry about Iraq’s stability: a prolonged conflict between the Mahdi Army and a rival Shiite militia for control of Shiite areas.

U.S. officials in Baghdad and Washington greeted word of the suspension cautiously, calling it an encouraging sign but saying it would take time to determine the impact of al-Sadr’s announcement.

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Some U.S. and Iraqi officials depict the Mahdi Army 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.

Al-Sadr said the Mahdi Army would suspend operations for up to six months while it was restructured, but many Iraqis wondered whether militia members would obey his directive. Witnesses to Tuesday’s clashes in Karbala said Mahdi Army fighters openly defied calls from a top al-Sadr official who was trying to calm the conflict.

Al-Sadr denied he had sanctioned Tuesday’s bloodshed and said he was halting militia operations to purge infiltrators and rogue elements engaging in attacks that discredit the populist force.

The militia has splintered into factions and needs to be “rehabilitated,” al-Sadr aide Hazim al-Araj i told Iraqi state TV.

Political analysts saw al-Sadr’s pledge to lay down weapons as damage control after the Karbala clashes instilled fears across the country that the prospect of multifactional civil war loomed.

“Al-Sadr is likely trying to deflect criticism for the clash in Karbala by blaming the event on rogue elements in the Mahdi Army,” said Vali Nasr, a Middle East studies fellow at the Council on Foreign Relations.

Nasr noted that, since a U.S. troop buildup began six months ago and its counterinsurgency operations have stepped up the pressure on Sunni extremists, the Madhi militia has been expanding and becoming better armed, likely with Iranian assistance.