Updated 9:26 a.m.
A rare car bomb ripped through a market in southern Iraq's Shiite heartland Wednesday as shoppers were buying meat and vegetables, killing at least 29 people and wounding dozens, officials said.
It is the deadliest bombing to hit the Nasiriyah area since Nov. 12, 2003, when a suicide truck bomber attacked the headquarters of Italian forces stationed there, killing more than 30 people.
The blast is the latest in a series of high-profile explosions that have raised concerns about a resurgence of violence as the U.S. military faces a June 30 deadline to withdraw from urban areas in Iraq.
The explosives-laden car was parked in the center of the commercial area in the town of Bathaa when it blew up about 9 a.m., according to police.
The town is near Nasiriyah, about 200 miles southeast of Baghdad.
The area has been the site of past violence - mainly fierce internal fighting between Shiite militia factions before a cease-fire took hold. But such bombings, which are the signature attacks of al Qaeda in Iraq, have been relatively rare.
Witnesses blamed lax security measures.
"We never expected such an explosion to occur here," said Amir Talib, 28, who witnessed the bombing and helped evacuate casualties in the aftermath. "It is a big security failure."
Authorities said they had increased security at the main entry points to the province and in the Nasiriyah city center to prevent the possibility of another bombing.
The U.S. military said Iraqi forces had secured the bombing site.
"All injured people have been sent to area hospitals. Police are collecting forensic evidence at the site," said Maj. Myles B. Caggins III, a spokesman for American forces in the area.
No one has yet claimed responsibility for the attack, but the U.S. military has warned that Sunni insurgents could be expected to try to foment sectarian violence in a bid to upset security gains ahead of the U.S. withdrawal.
Persistent violence as the Americans begin to withdraw has raised new questions about the readiness of Iraqi forces to take over their own security.
Iraq's Vice President Adel Abdul-Mahdi, a Shiite, blamed al Qaeda and nationalist insurgents.
"Targeting stable and secure areas is a desperate effort ... to reignite sectarian sedition and try to affect security and political progress," Abdul-Mahdi said in a statement.
Officials gave conflicting death tolls Wednesday, as is common in the chaotic aftermath of bombings in Iraq. They also faced the difficulty of gathering information from a comparatively remote small town.
Sajad Sharhan, the head of the security committee for the surrounding Dhi Qar province, said 29 people were killed and 55 wounded, including five in critical condition.
He also said a wounded man was under investigation because local residents claimed he was a stranger in the area. Sharhan stressed nobody had been charged, but the reports reflected the tight-knit nature of the small tribal community in Bathaa.
An Interior Ministry official, speaking on condition of anonymity because he's not authorized to release the information, put the death toll at 28.
A spokesman for the Nasiriyah hospital, Kadhim al-Obeidi, said 35 people were killed and 45 wounded.
Dhi Qar province, of which Nasiriyah is the administrative capital, was the second province to be transferred from U.S.-led coalition control to the Iraqis in September 2006.
A U.S.-Iraqi security pact that took effect on Jan. 1 requires all American forces to pull back from urban areas by the end of this month and from the entire country by 2012.
The Iraqi government has agreed to hold a national referendum on the agreement as required by parliament but said it wanted to hold the vote early next year instead of this summer as originally planned.
Tuesday's Cabinet decision, which needs approval from Iraq's parliament, means the referendum would be held together with national parliamentary elections on Jan. 30.
Government spokesman Ali al-Dabbagh said the move would "save time and money."
The inclusion of the referendum met a demand by the main Sunni bloc in parliament and raised the possibility that the deal could be rejected if anti-U.S. anger and demands for an immediate withdrawal grow.