Bombs targeting worshippers gathered for evening prayers at four Sunni mosques in Iraq killed 12 people, officials said.
A bomb exploded in the Omar bin Abdulaziz Mosqe on Tuesday in the northern city of Kiruk, while another blast struck near Al-Salihin Mosque close by, killing a total of seven people and wounding 31.
Two bombs exploded near Ahmed al-Mukhtar Mosque in the Dura area of south Baghdad, killing at least three people and wounding at least nine.
Another car bomb exploded near Al-Imam Ali Mosque in Kut, southeast of Baghdad, killing two people and wounding nine.
Special extended evening prayers (Tarawih) are held during the holy Muslim fasting month of Ramadan, which began two weeks ago.
Both Sunni and Shia places of worship have been attacked in recent months, raising fears of a return to the all-out sectarian conflict that killed tens of thousands of people in past years.
With the latest attacks, more than 630 people have been killed in violence so far this month, making July the deadliest month in a year marked by spiralling violence.