The latest attacks underscore the challenges Iraqi security forces face as US combat troops prepare to withdraw by August 31, 2010, with all US troops due to leave by the end of 2011.

Bombings continue on an almost daily basis in Iraq, despite the sharp fall in violence.

The last large bomb blast in Baghdad killed 20 people in a shopping district on March 26.

Preventing all car bombs in the crowded streets of Baghdad - a maze of crumbling buildings and concrete walls housing millions of people - is all but impossible.