The deadliest attack was in Baghdad's southeastern suburb of Nahrawan, where a roadside bomb went off in a busy street, killing at least seven civilians and wounding 15, a police officer said.
In the southeastern Zafaraniyah neighbourhood, the bodies of three workers were found inside a house under construction, another police officer said. All were shot in the head at close range.
In the northern city of Mosul, two suicide attackers rammed their explosives-laden cars into two military barricades, killing four soldiers and one civilian, another police officer said. Another 23 people were wounded. Mosul is 360-km northwest of Baghdad.
Two anti-Al Qaeda Sunni fighters were killed today and six wounded when a roadside bomb hit their car in the western Baghdad suburb of Abu Ghraib, police said.
The pro-government group called Awakening Council joined with US troops to fight Al Qaeda before the US pullout in late 2011. Since then, its members have been a frequent target for Al Qaeda in Iraq, which considers them traitors.
Four medical officials confirmed the casualty figures. All officials spoke on condition of anonymity as they were not authorised to talk to reporters.
Violence increased sharply in April and May, with frequent bombings in civilian areas raising concerns that a widespread sectarian conflict might once again break out in Iraq.
According to the United Nations mission in Iraq, last month's violence claimed the lives of 761 Iraqis and wounded 1,771 others.