The six killed on the outskirts of the holy shrine city of Karbala, 100 kilometres south of the capital, were making their way there as part of commemorations for the birth of a revered Muslim figure.

"A car bomb killed three people and wounded 20 people inside a bus station north of the city of Karbala," said General Othman al-Ghanimi, a security official in charge of security in the region.

Nazeer al-Rubayee of Karbala's Al-Hussein Hospital confirmed the toll, saying that the wounded included women.

At around 9:30 pm (1830 GMT) east of the city, another car bomb killed three worshippers and wounded more than 25, Karbala health department spokesman Jamal Mehdi said.

Thousands of pilgrims are headed to Karbala to mark Shahbaniyah, the birthday of a revered Muslim figure, which falls on either Saturday or Sunday, with the dates differing depending on interpretations of the lunar calendar.

In the Dora district of southern Baghdad, one person was killed and three wounded by an improvised bomb, an interior ministry official said.

Meanwhile, in another part of the same district, an explosion in the early hours of Friday killed one person in a house where police later found several improvised bombs and guns fitted with silencers.

Copyright AFP (Agence France-Presse), 2011