ZUBAIR, Iraq — Updated at 6:40 a.m. ET: The death toll from a suicide bomb attack on Shiite pilgrims in the southern Iraqi city of Basra rose to 50 people with another 100 wounded in the blast, Riyadh Abdul-Ameer, director of the Basra health office, tells Reuters.
Published at 5:20 a.m. ET: A bomb killed at least 30 Shiite pilgrims near the southern port city of Basra on Saturday, Iraqi officials said. It was the latest in a series of attacks during Shiite religious commemorations that threaten to further increase sectarian tensions just weeks after the U.S. withdrawal.
Basra hospitals have received 30 killed and 90 wounded after the blast, said Dr. Riyadh Abdul-Amir, the head of Basra Health Directorate. A police official confirmed the death toll. He spoke anonymously because he was not authorized to release details to the media.
Witnesses said the attack occurred outside the town of Zubair, southwest of Basra, as pilgrims were making their way to a Shiite shrine nearby. Zubair is a predominantly Sunni enclave in Iraq's largely Shiite south.
The governor of Basra province's spokesman, Ayad al-Emarah, said it was not clear whether the blast was caused by a suicide attacker or a roadside bomb.
The explosion came as Shiites commemorate the climax of Arbaeen, which marks the end of 40 days of mourning following the anniversary of the death of Imam Hussein, a revered Shiite figure.
Majid Hussein, a government employee, was one of the pilgrims heading to the shrine. He said people began running away in panic when they heard a loud explosion.
"I saw several dead bodies and wounded people, including children on the ground asking for help. There were also some baby strollers left at the blast site," he said.
"A terrorist wearing a police uniform and carrying fake police I.D. managed to reach a police checkpoint and blew himself up among police and pilgrims," a police official at the scene of the bombing said.
Reuters quoted two other officials who gave different death tolls of 32 and 35.
The attack, which bore the hallmarks of Sunni insurgents, is the latest in a series of deadly strikes in this year's Arbaeen. Scores of pilgrims have been killed.
The largest of the Arbaeen attacks — a wave of apparently coordinated bombings in Baghdad and outside the southern city of Nasiriyah — killed at least 78 people on Jan. 5. It was the deadliest strike in Iraq in more than a year.
The attacks raise fears of a new sectarian rift that could destabilize the country now that U.S. troops are gone.
U.S. troops left last month
The last U.S. combat troops left Iraq on Dec. 18, ending a nearly nine-year war. Many Iraqis worry that a resurgence of Sunni and Shiite militancy could follow the Americans' withdrawal. In 2006, a Sunni attack on a Shiite shrine triggered a wave of sectarian violence that pushed the country to the brink of civil war.
Just as the American troops were leaving, a political crisis erupted that has paralyzed Iraq's government. It pits the country's mostly ethnic- and religious-based political blocs against one another.
Iraq's Sunni minority dominated the government under the dictatorship of Saddam Hussein, but since he was overthrown, Shiites have controlled most key posts.
The political dispute appears far from being resolved.
On Friday, Deputy Prime Minister Saleh al-Mutlaq called for Iraq's leader, Prime Minister Nouri al-Maliki, to step down or face a parliamentary vote of no-confidence. Al-Mutlaq's Sunni-backed Iraqiya party has been boycotting parliament and Cabinet meetings since last month to protest what it sees as efforts by al-Maliki to consolidate power, particularly over state security forces.
Al-Maliki's government, meanwhile, has demanded the arrest of the country's top Sunni politician, Vice President Tariq al-Hashemi of Iraqiya, accusing him of running a hit squad targeting government officials. Al-Hashemi denies the allegations.
The Associated Press and Reuters contributed to this report.