Iraqi security forces launched a crackdown on Shi'ite militias in the southern city of Amara Thursday, the latest drive in Prime Minister Nuri Al-Maliki's campaign to restore order to Iraq. “The operation started this morning,” Major-General Tareq Abdul Wahab, the commander of the offensive, said. He declined to give further details. Amara, home to 250,000 people, is a stronghold of the Mehdi Army militia of anti-American Shi'ite cleric Moqtada Al-Sadr. Police said they had started raiding houses of suspected militants in Amara's town centre and eastern suburbs. They said they met no resistance and residents said they had not yet heard a single gunshot. Sadr has ordered his fighters not to resist. Iraqi troops and police have been tightening their grip on Amara for days. They have urged militias to hand over medium and heavy weapons, such as rockets and mortars. Maliki has already sent the Iraqi army, with US support, into Mehdi Army bastions in Baghdad and the southern oil city of Basra, and launched a campaign against Al-Qaeda insurgents in the northern city of Mosul. Scores of Iraqi police and troops patrolled the streets of Amara and US helicopters hovered overhead. Many residents stayed home and some shops were closed. Traffic jams built up on Amara's outskirts as police searched vehicles entering the city. Maliki had given those whom he called “outlaws” and “criminals” in Amara until Wednesday to surrender their heavy weapons ahead of the crackdown. A security source has said militants were instead dumping them in rivers, streets or farms. The Baghdad and Basra operations initially appeared to have backfired, as government forces met fierce resistance from Mehdi Army fighters. Hundreds were killed in Basra and other southern towns and fighting raged in Baghdad for nearly two months. However, government control has been largely restored in both. Maliki has been criticized in the past for lacking resolve to stabilize Iraq – especially in cracking down on fellow Shi'ites. But he has gained a measure of respect at home and abroad for the offensives, which have helped reduce violence to the lowest level in more than four years.The campaigns also underscore the government's desire to take more control of security from the 150,000 US troops in Iraq. Baghdad is negotiating a security pact with Washington to lay the legal foundation for U.S. forces to remain in Iraq beyond a UN mandate that expires at the end of this year. The talks have proved controversial in Baghdad and Washington. In a sign recent security gains are fragile, a truck bomb killed 63 people in Baghdad Tuesday. The US military blamed Shi'ite militants for the attack.