Anti-US cleric Muqtada al-Sadr announced Friday that he has extended a cease-fire order to his Shi'ite Mahdi Army by another six months, giving Iraq a chance to continue its fragile recovery from brutal sectarian violence. His message was sent to by Shi'ite clerics during prayer services in mosques dominated by followers of the black-turbaned cleric. "According to an order by Sayyid Muqtada, activities of the Mahdi Army will be suspended ... for another six month period," al-Sadr's aide Hazim al-Aaraji said, using an honorific during his sermon at the Kazimiyah mosque in Baghdad. Al-Sadr's decision to halt the activities of his powerful militia for up to six months last August was one of three critical steps that have been widely credited with bringing the Iraqi death toll down more than 60 percent in recent months. The other pieces of the puzzle are the so-called surge of US troops and the move by US-backed Sunni fighters to switch allegiances and start working against al-Qaida in Iraq. The US military welcomed initial word of the decision, but pledged to continue cracking down on what it calls breakaway factions that persist in violence. "This extension of his August 2007 pledge of honor to halt attacks is an important commitment that can broadly contribute to further improvements in security for all Iraqi citizens," the military said in a statement. "It will also foster a better opportunity for national reconciliation and allow the coalition and Iraqi security forces to focus more intensively on al-Qaida terrorists." "Those who continue to honor al-Sayyid Muqtada al-Sadr's pledge will be treated with respect and restraint," it said. "Coalition and Iraqi security forces will continue to work closely with the Iraqi people to protect them from these criminals who violate the law and dishonor the commitment made by al-Sayyid Muqtada." The military also said it was open to dialogue with the Sadrists and "all groups who seek to bring about reconciliation in building the new Iraq." The American military has continued to raid Shi'ite groups it says are supported and trained by Iran and have splintered off from al-Sadr's militia. That's angered some followers of Sadr, who also are frustrated with the Iraqi government, and they argued for an end to the cease-fire. An according to an AP count, at least 609 Iraqi civilians and security forces died in Iraq last month, compared to 1,920 killed in January 2007. Al-Sadr's surprise decision to stand down his Mahdi Army for up to six months was designed to stop a Shi'ite-Shi'ite rift from spiraling out of control and to weed out infiltrators in his militia's ranks, according to aides of the radical Shi'ite cleric. Al-Sadr issued his order to his fighters to stand down for up to six months on Aug. 29, days after deadly clashes in the holy city of Karbala between his Mahdi Army and the rival Badr militia of the Supreme Iraqi Islamic Council, the country's largest Shi'ite party and a US partner. Involvement in inter-Shi'ite fighting has hurt the image of al-Sadr and his Mahdi Army, chipping away at the young cleric's reputation as an uncompromising nationalist leader seeking to restore Iraq's full sovereignty and undermining his bid to become a national leader. Aides at the time said the cease-fire was designed to stop a Shi'ite-Shi'ite rift from spiraling out of control and to weed out infiltrators in his militia's ranks. Meanwhile, a bomb hidden under a cart exploded in downtown Baghdad on Friday, killing two civilians and wounding six, police said. The cart was left near a building, and the explosives apparently were detonated by remote-control at about 7:30 a.m. Three cars parked nearby were damaged. A booby-trapped car being towed by police also blew up in Saddam Hussein's hometown of Tikrit, killing two policemen and wounding four others, police said. Police said they were removing the car after it was found parked near a market pockmarked with bullet holes and with bloodstained seats. The explosion occurred about 8 a.m. as it was being pulled into the parking lot of the local police headquarters, officials said. Tikrit is 130 kilometers north of Baghdad. The police officials all spoke on condition of anonymity because they weren't authorized to release the information. Nobody claimed responsibility for the attacks. The US military has warned suspected Sunni insurgents led by al-Qaida are seeking new ways to avoid stepped-up security measures that have dampened their ability to stage high-profile car bombings and suicide attacks.