Gunmen killed 12 people in a series of shootings in Iraq's main northern city of Mosul on Sunday, a police officer said.
Police Major Mohammed Ahmed said the 12 dead included a dentist, a civil servant, a student and an officer of the former Iraqi army.
Five people were killed in attacks elsewhere in Iraq.
One person was killed and six wounded when a Katyusha rocket was fired into the northeast Baghdad neighbourhood of Mustansiriyah, a security official and a medic said.
Another person was killed and six others wounded in a roadside bombing in central Baghdad.
South of the capital, three people were killed near the town of Musayyib when gunmen opened fire randomly on a group of civilians in the village of Tunis, a local police officer said.
The defence ministry said Iraqi troops arrested at least 82 militants, including dozens linked to Al-Qaeda, in a series of operations across Iraq.
"The army arrested 50 terrorists, many linked to Al-Qaeda, in Diyala province," a ministry statement said.
It said the security forces also found 2,000 Katyusha rockets during the operations in Diyala.
The confessionally divided province northeast of Baghdad is currently the second most dangerous in Iraq after the capital itself.
The ministry said "32 terrorists were also captured and seven cars full of explosives seized from Abu Ghraib", on the western outskirts of Baghdad.