In Anbar province, west of Baghdad, a suicide bomber detonated an explosives-rigged vehicle near an army checkpoint at an entrance to the town of Heet at about 7:30 am (0430 GMT), killing three soldiers and wounding five.
Militants frequently carry out attacks against security forces and other government employees.
While the mostly Sunni Anbar province was home to militant strongholds in past years, it has been relatively quiet in recent weeks, with most of the latest violence seen in Baghdad and several northern provinces, which are more confessionally and ethnically mixed.
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Another suicide bomber blew up a vehicle near a police checkpoint in Salaheddin province, north of Baghdad, killing three people and wounding seven, while a roadside bomb near the home of a Shiite family in Diyala province's capital Baquba killed one person and wounded two.
Members of Iraq's Shiite majority are frequently targeted by Sunni militants, who consider them apostates.
Violence has reached a level unseen since 2008, and there are fears Iraq may relapse into the kind of intense Sunni-Shiite bloodshed that peaked in 2006-2007 and killed tens of thousands of people.
With the latest violence, more than 60 people have been killed in attacks so far this month, and over 4,750 since the beginning of the year, according to AFP figures based on security and medical sources.