Iraq said on Friday that it hopes other armed groups will follow Shiite cleric Moqtada al-Sadr's decision to freeze his militia as Sunni Arabs expressed optimism the ban would reduce attacks on them.
The suspension of the dreaded Mahdi Army's activities was "an opportunity for other militias of different political affiliations" to lay down their arms and help reduce bloodshed in the country, the prime minister's office said.
On Wednesday, Sadr ordered the militia to suspend its activities for six months after allegations that it was involved in deadly firefights in the shrine city of Karbala during a major Shiite festival the previous day.
At least 52 people died and 300 were wounded in Tuesday's clashes between police and gunmen which forced authorities to abort a revered Shiite pilgrimage.
Sadr denied any role in the violence but quickly ordered a freeze on his militia.
Prime Minister Nuri al-Maliki's office said his decision would help in stabilising Iraq and be an example for other militant groups.
"The Sadr movement is an important political power in Iraq and will remain active in the political process," the premier's office said.
The statement was at pains to stress that Baghdad was not blaming Sadr's men for the Karbala carnage but only expecting them to "chase those elements who committed the crimes."
Over the past 18 months, the Mahdi Army has been accused of slaughtering Sunni Arabs since the brutal Shiite-Sunni sectarian conflict broke out in February 2006.
Iraq has around a dozen militias loyal to various political groups, and infighting between them has often caused violence to spill out on the streets.
Particularly intense has been the reported violence between the Mahdi Army and the Badr Organisation, the militant wing loyal to the Supreme Iraqi Islamic Council (SIIC) party headed by powerful Shiite politician Abdel Aziz al-Hakim.
The group's mutual distrust was evident during Friday prayers at Baghdad's Kadhimiyah mosque when Sheikh Osama al-Tamimi, a representative of Sadr, said the Karbala carnage was a "conspiracy" by SIIC to blame the Sadr group.
The US military said American soldiers and Iraqi forces had arrested 11 suspected extremists in Karbala since Wednesday.
It was not known whether the detained people were involved in the Karbala firefights.
The Imam Hussein shrine in Karbala, meanwhile, saw a few hundred Shiites attend Friday prayers amid tight security. The shrine usually sees thousands of devotees on Friday.
Leading the prayers, imam Abdel Mahdi Karbalae, a representative of senior Shiite cleric Grand Ayatollah Ali al-Sistani, called Tuesday's clashes the result of an "organised" plan.
"We have intelligence information which indicates there was an organised plot to cause clashes and create chaos," he told the congregation, holding up a letter from "intelligence sources."
He did not say who allegedly masterminded the fighting.
Sunnis gave a cautious welcome to the Mahdi Army truce call.
"If the call involves stopping displacement (of Sunnis) and burning mosques, it would be a good step," said Omar Abdul Sattar Mahmud, a legislator from the Iraqi Islamic Party, a key Sunni parliamentary group.
Iraq's sectarian conflict has seen dozens of Sunni and Shiite mosques destroyed in tit-for-tat attacks.
The Sunni Muslim Scholars Association, a religious body accused of having links with anti-American insurgent groups, gave a mixed reaction to Sadr's ban.
"If the (Mahdi) Army drops resisting the occupiers then it would be a wrong decision and Sayid Moqtada or anyone else has no right to give such an order," said association spokesman Mohammed Bashar al-Faydhi.
But if the "order is meant to stop the bloody activities of the Army against innocent people, the displacements and killings, then it is a sound decision."
The US military said insurgents killed two more American troops in the Sunni province of Anbar, taking its losses since the March 2003 invasion to 3,731.
A US congressional delegation returned safely to Washington after their plane evaded fire from the ground as it flew them out of Baghdad on Thursday, the military said.
Iraq also announced on Friday that 50 detainees will be released every day from US-run prisons during the Muslim fasting month of Ramadan starting around September 12.
Some 20,000 detainees are held in US-run prisons in Iraq, most of them without charge.