Bomb blasts killed more than 30 people on Saturday on the second day of the Islamic Eid al Adha religious festival.
Two car bombs destroyed parts of Baghdad's Shi'ite neighbourhood Sadr City and police said a bomb device was also strapped to a bus full of Iranian pilgrims on their way to a shrine.
It exploded around 300 metres (yards) from a police checkpoint, sending the bus out of control before it flipped over on its side.
Violence in Iraq has eased in recent times, but Sunni Islamist insurgents and al Qaeda's Iraq wing often target Shi'ites in an attempt to stir up the kind of sectarian tensions that dragged the country close to civil war in 2006-2007.
More top news
Tesco recalls own-brand squash after customers complain of "disgusting taste" and parents worry it may have caused children's stomach upset.
Bradford City co-chairman Mark Lawn has blasted TV broadcasters over their FA Cup fifth round match choices
Face to face with 2 tons of unpredictable muscle is an awe-inspiring moment but within a few years it will be impossible, they will be gone.