Two people were killed and five were injured when a bomb inside a minibus exploded at a market in Baghdad's predominantly Shia district of Sadr City.
Police first said the blast was caused by a car bomb.
Sadr City, in eastern Baghdad, is a stronghold of radical Shia cleric and militia leader Moqtada al-Sadr, who is a member of the ruling Shia coalition.
Seven car bombs exploded in the Iraqi capital yesterday, killing at least eight people and wounding 80.