Seven people were killed and at least 50 injured in a car bomb blast on Saturday in Najaf city, 180 km south of Baghdad, Iraqi police said.
Most of the victims were Iranian pilgrims.
A security source told DPA that "a car laden with explosives was parked in the garage containing tour buses carrying Iranian pilgrims, about one kilometre from the shrine of Imam Ali bin Abi Talib".
"The car exploded, killing seven people, four of them Iranian, and wounding 50, including 37 Iranians. Four buses were burned."
The attack comes a day ahead of Iraq's parliamentary elections.