At least four people were killed and 15 wounded when a suicide bomber blew himself near a Shiite mosque in Musayyib, south of Baghdad.
The bombers victims were all civilians who were leaving the mosque or passing by.
The attack comes one day after suicide bombers killed at least 79 people praying at a Shiite mosque in Baghdad.
On Friday, the Interior Ministry issued a statement warning the public that they had received intelligence that insurgents were preparing to detonate several car bombs in and around Baghdad.
They advised people to stay away from crowded areas.
