A total of 27 bodies were found around Baquba, 65km north of Baghdad, police said.
Fifteen decomposing bodies were found in a field.
Munzir Baig, Muscat, Oman
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All were handcuffed and had bullet wounds.
Another 12 bodies with bullet wounds and showing signs of torture were found in different areas.
Also on Saturday, police said armed men abducted an oil facility security official and his driver in Baiji, 180km north of Baghdad.
In Khalis, a town 80km north of Baghdad, a suicide car bomber aiming to strike a military checkpoint killed one soldier and wounded three others, police said.
Police also said armed men killed a former senior intelligence officer in Mosul, 390km north of Baghdad.
While US commanders say the number of sectarian death squad murders has declined by about a third since the Baghdad security plan was launched, a series of large bomb attacks have kept the overall level of casualties roughly the same.
In Saydiya, a mixed district, unidentified assailants shot dead five civilians and wounded one, while in al-Risala, a mainly Shia district in the south, a series of mortar rounds slammed into a residential area killing three people and wounding 10 others, including women and children, a police official said on Saturday.
In Baghdad's predominantly Shia neighbourhood of Kadhimiya, a civilian was killed and three others were injured when a homemade bomb blew up in a public market, a police source said.
For its part, the US military said on Saturday that US forces captured 17 suspected fighters during a series of overnight raids against al-Qaeda fighters across Iraq.
It also said that a US aircraft destroyed a truck bomb loaded with explosives east of Garma, near Falluja, on Friday.
Iraqi police said a suicide truck bomber killed 10 people and wounded 20 others on Friday in Hit, about 140km west of Baghdad.
Against this backdrop of continued violence, small crowds of Iraqi Sunni Arabs gathered in neighbourhoods of northern Iraq to mark Saddam Hussein's first birthday since his execution.
Around 200 local residents, mostly children between the ages of seven and 12, gathered at the former Iraqi president's tomb in Awja, his home town, on Saturday.
The farming village lies just outside the city of Tikrit, 180km north of Baghdad.
He was laid to rest there after being hanged on December 30 for crimes against humanity.
Ali al-Nida, the chief of the Baijat tribe to which Saddam belonged, attended the ceremony after initially urging his people to keep the celebrations small or even to postpone them.