- NEW: Pilgrims are also targeted in the Shiite heartland
- Three bombs explode in Sadr City
- Two more explode in northern Baghdad Shiite area
- Fears intensify over Sunni-Shiite sectarian violence
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 "terrorist groups take every chance they get to incite sectarianism."
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 in were pilgrims. The city is located in Thiqar province, police and an Interior Ministry official said.
A triple bombing in Baghdad's Sadr City area Thursday morning killed at least nine people and wounded 35 others, 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.
In other violence, 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 apart.
Kadhimiya is busy with many Shiite pilgrims who started their pilgrimage walking to Karbala, and security has been jacked up because of the event, which culminates later this month.
Atta said that 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.