The bomber detonated an explosives-rigged vehicle during rush hour yesterday, the first day of the working week in Iraq, at a checkpoint at the northern entrance to the city of Hilla.
Among the dead were five policemen and two state television employees. The blast also left 153 others wounded, according to the sources, who spoke on condition of anonymity.
An interior ministry statement said the bomber had used an explosives-rigged tanker truck in the attack.
Iraq has been hit by a year-long surge in violence that has reached levels not seen since 2008, driven principally by widespread discontent among its Sunni Arab minority and by the civil war in neighbouring Syria.
Analysts and diplomats have urged the Shiite-led authorities to reach out to disaffected Sunnis, but with elections due next month, political leaders have not wanted to be seen to compromise and have instead pursued a hard line against militants.