Seven Iraqi policemen have been killed in an attack on a police checkpoint in the town of Baquba, 60km (35 miles) north-east of Baghdad, police say.
Up to 10 people were also wounded when insurgents attacked the al-Razi checkpoint with rocket-propelled and hand grenades and small arms fire.
Baquba's Diyala province has suffered a number of attacks on police facilities.
Baquba is a mixed Sunni-Shia town and has also seen a number of sectarian bomb attacks on shrines.
The Associated Press news agency also reported that eight severed heads were found on a road near Baquba.
It said a note was found accusing at least one of the dead men of killing four Shia doctors.
In other violence, at least four bodies were found across Baghdad, all with signs of torture.
And two policemen were wounded when a roadside bomb struck their patrol in eastern Baghdad.
The violence comes as the new government of Prime Minister Nouri Maliki prepares to name the new interior and defence ministers - a move the administration hopes will help ease unrest.