Security and medical sources said on Wednesday an army colonel protecting oilfields was shot dead near the disputed northern city of Kirkuk while he was on patrol.
Police said Colonel Ibrahim Ahmad was killed in his car in the town of Ajil, west of Kirkuk.
Two fires broke out on oil pipelines in the same area. "The first is under control and the other one not yet," an oil company source said, adding that sabotage was the most likely cause of the fires.
Near Dhuluiya, north of the capital Baghdad, three Iraqi soldiers were killed and two others wounded by a bomb concealed in the burnt-out shell of a car abandoned on the roadside.
In Dujail, also north of the capital, two Iraqi soldiers and an Iraqi contractor were killed in a mortar attack on an army base, police said.
Clashes broke out overnight in the town of Baquba, leaving one Iraqi policeman and two armed men dead, security sources said. The fighting lasted most of the night.
Police also said two fighters were killed and two others captured in clashes with US troops in the Sunni town of Samarra.
In the northern town of Mosul, police Lt-Col Halab Abd al-Rahman escaped an assassination attempt that killed his driver and wounded his bodyguard, police said.
Iraqi police have been frequent
targets of anti-US fighters
In other violence, an Iraqi woman was killed near the town of Tuz and her husband wounded when Iraqi forces manning a ckeckpoint apparently opened fire on their vehicle.
"The couple's vehicle was driving at high speed which is apparently why it was engaged," police Captain Ahmad Bayan al-Din said.
Also, the US military announced that a soldier was killed in action on Tuesday in the violence-wracked western province of Anbar.
Anbar province is a huge area stretching west of the capital to the Saudi, Jordanian and Syrian borders, and includes the Sunni strongholds of Falluja and Ramadi.
Tuesday's death brings to 1457 the total number of US servicemen who have died since the March 2003 invasion of Iraq, according to Pentagon figures.