Iraqi officials say three bombings in the country have killed 34 people as U.S. Defense Secretary Robert Gates began a visit to Baghdad.
In Monday's deadliest attack, a female suicide bomber blew herself up at a dinner party attended by Iraqi police in Diyala province, killing 22 people and wounding more than 30.
In Baghdad, two car bombs went off in quick succession in the central district of Karrada, killing 12 people and wounding at least 30. The U.S. military blamed the attack on al-Qaida in Iraq.
U.S. Defense Secretary Gates arrived in Baghdad a day before a new commander takes charge of the U.S. military in Iraq. Gates says Lieutenant-General Raymond Odierno will be tasked with expanding Iraq's security gains as U.S. troop levels fall.
Gates also says the areas in which U.S. forces will be engaged in Iraq will continue to narrow.
In Baghdad, Gates presented medals to the departing U.S. commander in Iraq, General David Petraeus, and to U.S. ambassador to Iraq, Ryan Crocker. Gates praised the men for helping, in his words, to "transform" Iraq into a better place.
Gates also held talks with Iraqi Prime Minister Nouri al-Maliki and other officials.
The number-two U.S. commander in Iraq told reporters it would be a mistake to push U.S.-trained Iraqi forces to take charge of security before they are ready. Lieutenant-General Lloyd Austin says the U.S. tried such a strategy prior to 2007, but it did not work.
Monday's suicide bombing in the town of Balad Ruz targeted a dinner hosted by an Iraqi officer to celebrate his release from a U.S. military prison. The blast killed the officer, some of his relatives and several other senior policemen.
Some information for this report was provided by AFP, AP and Reuters.