Militants targeted Iraqi soldiers and anti-Al-Qaeda militiamen on Sunday as attacks killed at least 11 people, including a child, security and medical officials said.
The attacks come as Iraq suffers its worst violence since 2008, when the country was just emerging from a brutal period of sectarian killings.
In Abu Ghraib, west of Baghdad, gunmen attacked a Sahwa militia checkpoint, killing at least four fighters and wounding at least three.
The Sahwa are made up of fighters who joined forces with the United States against the jihadists from late 2006, helping to bring about a significant reduction in violence.
They are frequently targeted by Sunni Muslim militants, who consider them traitors.
In the northern city of Mosul, a car bomb exploded near an army checkpoint, killing four soldiers, while a roadside bomb in the city killed a child and wounded three people.
Mosul is one of the most dangerous parts of Iraq, with militants carrying out frequent attacks and also reportedly extorting money from businesses.
And in Baghdad itself, a roadside bomb exploded in the Jihad area, killing at least two people and wounding six.
More than 6,750 have been killed in violence since the beginning of 2013, according to AFP figures based on security and medical sources.
Analysts say widespread discontent among Sunni Arabs over what they see as discrimination at the hands of the Shiite Arab majority who lead the government is a major factor in the heightened violence.
On Saturday, security forces raided the home of Sunni Arab MP Ahmed al-Alwani, who backs anti-government protesters, arresting him and sparking clashes that killed his brother and five guards.