Baghdad ( CNN ) -- Attackers killed at least 60 people in Iraq on Thursday in strikes that targeted Shiites and renewed fears of sectarian violence , authorities said . The deadliest attack was a suicide bombing targeting Shiite pilgrims just west of the southern city of Nasiriya . It killed at least 36 and wounded 72 others , police and Interior Ministry officials said . A series of blasts in Baghdad left 24 dead and dozens wounded , an Interior Ministry official said . The violence raged as Shiites made a pilgrimage to the city of Karbala , south of Baghdad , leading up to Arbaeen , one of the holiest days of the Shiite calendar . It arrives next week and marks the end of a 40-day mourning period for Imam Hussein , a grandson of the Prophet Mohammed , who was killed in a seventh century battle in the Iraqi city . Gen. Qassim Atta , the Iraqi commander of Baghdad security operations , said that `` terrorist groups take every chance they get to incite sectarianism . '' Martin Kobler , the U.N. special representative in Iraq , condemned the strikes and urged Iraqis to `` remain steadfast in the face of those who are using violence '' and trying to undermine the country 's efforts to succeed as a democracy . `` These casualty figures are people , women and men , the youth of the country and its children . These are mainly civilians , and one life taken per day is one life too many . And this has to be stopped , '' Kobler said . Violence raged for years after the U.S. invasion of Iraq between members of Iraqi 's Sunni minority , who held power during the era of Saddam Hussein , and its Shiite majority , which gained power after his ouster . Iraqis have been concerned about an increase in Sunni-Shiite violence after the U.S. military withdrawal from the country last month . Sunnis in Iraq have felt marginalized by the government of Prime Minister Nuri al-Maliki , a Shiite . That anger intensified after he ordered the arrest last month of Sunni Vice President Tariq al-Hashimi , who was charged with ordering bombings and assassinations , a charge he denies . The bomber in Nasiriya struck an Iraqi Army checkpoint where buses carrying pilgrims were parked . Most of the casualties were pilgrims , police and an Interior Ministry official said . The city is located in Thiqar province . A triple bombing in Baghdad 's Sadr City area Thursday morning killed at least nine people and wounded 35 , an official with Iraq 's Interior Ministry said . The first bomb -- attached to a motorcycle -- detonated near a group of laborers who were searching for day jobs in the Shiite neighborhood , according to the official . Shortly after that , two other bombs detonated in quick succession nearby . The sprawling neighborhood of Sadr City is a Shiite enclave . Car bombs exploded successively in northern Baghdad 's predominantly Shiite Kadhimiya district on Thursday morning , killing 15 and wounding 31 , the Interior Ministry official said . The bombs exploded in two busy squares that were about 150 meters ( nearly 500 feet ) apart . Kadhimiya is busy with many Shiite pilgrims who started their pilgrimage walking to Karbala , and security has been jacked up accordingly . Atta said it was too soon to tell who was behind what appeared to be coordinated attacks in Baghdad . However , he said he believes it was `` what remains '' of terrorist groups trying to incite sectarian rifts . Iraq has a large Shiite population in the capital and across southern Iraq . Iraq has been engulfed in political turmoil that has threatened to unravel the government . Al-Hashimi said al-Maliki 's charges against him were politically motivated and fled to the semi-autonomous Kurdish region . His arrest warrant was issued just days after the Iraqiya bloc suspended its participation in parliament amid complaints it was being cut out of the political process . Iraqiya , a cross-sectarian as well as Sunni-backed bloc , castigated the al-Maliki government , saying it had shunned cooperation despite the power-sharing arrangement . It said it is considering sending a request to parliamentary leaders to withdraw support for al-Maliki and come up with a new prime minister to form a post-occupation government . There have also been mounting calls for federalism from at least three predominantly Sunni provinces . Al-Maliki has called federalism a recipe for the partitioning of Iraq . The bloc loyal to the radical Shiite cleric Muqtada al-Sadr , a key ally to al-Maliki , has called for the dissolution of parliament and early elections . Al-Maliki managed to forge a fragile coalition and secure a second term in office because of backing from followers of al-Sadr , the powerful leader of the notorious Mehdi Army that fought some of the fiercest battles against U.S. forces .
NEW : Pilgrims are also targeted in the Sunni heartland . Two bombs explode in Baghdad . Two more explode in northern Sadr City Shiite area . Fears intensify over Shiite -Shiite sectarian violence .