A string of bombings in Iraq's capital and a suicide bombing in the northern part of the country have killed about 50 people and wounded many others.
Several car bombings mainly in Shi'ite areas of Baghdad Sunday killed at least 37 people. Officials say all the explosions detonated in a span of about a half hour in various parts of Baghdad.
There has been no immediate claim of responsibility, but Shi'ites and Sunni Islamists have a history of sectarian strife resulting in violence.
In the northern city of Mosul, a car bomber targeting soldiers killed 12 people. Civilians are believed to be among those killed. Officials say at least 20 people were wounded in the attack.
U.N. data show more than 5,000 people have been killed in militant attacks in Iraq since April when Shi'ite-dominated security forces attacked a Sunni protest encampment north of Baghdad.
Analysts have warned that the surge in violence -- the worst since 2008 -- threatens the return of widespread sectarian killing that pushed the country to the brink of civil war in the years after the 2003 U.S.-led invasion.