ZUBAIR, Iraq -- A bomb tore through a procession of Shia pilgrims heading toward a largely Sunni town in southern Iraq on Saturday, killing at least 53 people in the latest sign of a power struggle between rival Muslim sects that has escalated since the American military withdrawal.
Fears of more bloodshed have risen in recent weeks, with the United States no longer enjoying the leverage it once had to encourage the two sides to work together to rein in extremists. Most of the latest attacks appear to be aimed at Iraq's majority Shia, suggesting Sunni insurgents seeking to undermine the Shia-dominated government are to blame.
Yesterday's blast happened on the last of the 40 days of Arbaeen, when hundreds of thousands of Shia pilgrims travel to the Iraqi city of Karbala and other holy sites. The end of Arbaeen is one of the most sacred times for the Shia, and public processions to commemorate it were banned under Saddam Hussein.
The blast hit near the town of Zubair as pilgrims marched from the port city of Basra toward the Imam Ali shrine on the outskirts of the town, said Ayad al-Emarah, a spokesman for the governor of Basra province.
The shrine is an enclave within an enclave -- a Shia site on the edge of a predominantly Sunni town in an otherwise mostly Shia province.
There were conflicting reports of what caused the blast, with some officials saying a roadside bomb was to blame.
But witnesses at the scene described the perpetrator as a suicide bomber disguised as a volunteer handing out juice and food to pilgrims. Ali Ghanim al-Maliki, the head of the Basra provincial council, corroborated that account in an interview with Iraqiya state television.