18 Iraqi National Guards and a civilian have been killed in a bomb attack on a bus at a US military base north of Baghdad.
A vehicle packed with explosives blew up next to the bus in the town of Balad.
The attack happened in the area known as the Sunni Triangle, which has been the scene of repeated violence.
It is the latest in a series of suicide attacks on Iraq's fledgling security forces aimed at disrupting elections later this month.
