A suicide bomber driving a minibus packed with explosives on Sunday killed at least 40 people and injured scores of others in an attack in the southern city of Hilla, about 100 kilometers (60 miles) from Iraq's capital, Baghdad, police and medical sources said.
A police officer said the attacker approached a main checkpoint at a northern entrance to the largely Shiite Muslim city before detonating his explosives.
Dozens of cars were set alight by the explosion, and part of the checkpoint complex was also destroyed, the officer said.
The attack took place during morning rush hour, when the checkpoint was crowded with people.
Prime Minister Nuri al-Maliki has meanwhile accused the Sunni Gulf states Saudi Arabia and Qatar of being partly responsible for the latest surge of violence afflicting Iraq.
In an interview broadcast on Sunday, he told France 24 that the two neighbors were supporting militants in Iraq, and had effectively declared war on the country.
"I accuse them of inciting and encouraging the terrorist movements. I accuse them of supporting them politically and in the media, of supporting them with money and by buying weapons for them," he said.
"I accuse them of leading an open war against the Iraqi government," he added, warning that their "support of terrorism" could backfire on them.
Iraq is currently experiencing violence at levels not seen since 2008, with almost daily attacks believed to be carried out by militants from among the country's Sunni minority. The UN estimates that 8,868 people died in attacks last year, the highest annual toll in Iraq in five years.
The new wave of killings is thought to be spurred by widespread discontent among Sunnis in Iraq and by the civil war in neighboring Syria.
tj/kms (AFP, dpa)