BAGHDAD, Iraq (CNN) -- Anti-American Shiite cleric Muqtada al-Sadr has ordered a suspension of his Mehdi Army militia for up to six months for restructuring, a senior aide said Wednesday.
Iraqis carry the coffin of a pilgrim killed in Karbala clashes during a funeral Wednesday in Najaf.
The move follows battles in Karbala and other cities between the Mehdi Army and Badr Organization, the armed wing of the Supreme Islamic Council of Iraq -- hostilities that left more than 50 people dead and scores injured.
Hazem al-Araji, who read the cleric's order on Iraqi state TV, said it applies to all members of the fighting force.
"For the sake of public interest, we have decided to issue the following: Suspend the Mehdi Army, with no exception, for a maximum of six months starting from the date of this release, to restructure it in a way that would preserve its ideological principles," al-Araji said. Watch an analysis of the Mehdi Army suspension »
He announced three days of mourning and the closing of all of al-Sadr's offices for the same period of time to condemn the events in Karbala. That three-day period begins Thursday. He also called for an investigation into the Karbala fighting.
In response, Lt. Col. Christopher Garver, a U.S. military spokesman, said, "We have always said we welcome those who want to participate positively in the future of Iraq."
He added that "U.S. forces welcome anyone and any leader who attempts to bring down the violence and rein in criminal behavior."
The suspension order raises questions about how much weight al-Sadr's decree will carry with the factions aligned with his fighting force.
The cleric has openly opposed violent actions before. On Tuesday, he called for calm and urged his followers not to attack rivals' offices.
But observers suspect many Mehdi Army fighters are more radical than al-Sadr. The U.S. military, when announcing arrests of Mehdi Army fighters, often refers to them as "rogue" members.
A top Iraqi official used that terminology Wednesday discussing the fighting in Karbala.
Mowaffak al-Rubaie, Iraq's national security adviser, said the hostilities were spurred by "rogue" elements of the Mehdi Army and other "extremists" who want to bring down the government.
"And we have started to clean the Iraqi security police and the army from those elements that have infiltrated the police in particular," he said.
Al-Rubaie said both Shiite and Sunni extremists are working to undermine a "national reconciliation" government.
He said Iraqi security forces are in control in the aftermath of the fighting in Karbala, where hundreds of thousands of Shiite pilgrims converged to commemorate the birthday of the revered historic 12th imam.
The clashes prompted the evacuation of many pilgrims, who fled to places such as Hilla and Najaf, prompting authorities to impose security measures, including a stiff daytime curfew in Karbala.
Hostilities between Shiites extended to other regions, such as Baghdad and Babil, where attackers torched at least 10 Supreme Islamic Council of Iraq offices. Eleven people, at least five in Baghdad and at least six in Babil, were killed.
Al-Rubaie called the suspension of the Mehdi Army "good news" if it turns out to be true. "We want to see it happening on the ground," he said.
CNN's Jomana Karadsheh and Yousif Bassil contributed to this report.