A US soldier was also killed and three wounded in a roadside bomb attack south of Karbala, in southern Iraq.
The surge in violence came against a background of growing bickering among Iraq’s ethnic and religious factions on how to form a government of ‘national unity’ following December general elections that gave religious Shia parties a majority in the 275-seat parliament.
US Ambassador Zalmay Khalilzad, at a news conference, warned that polarisation along ethnic and sectarian lines was ‘the fundamental problem’ in Iraq, adding that the insurgency was taking advantage of the upheaval.
In the day’s bloodiest attack, a suicide bomber blew himself up killing 12 commuters in a minibus in a Shia neighbourhood of northern Baghdad, an interior ministry official said.
Rescue teams combed the vehicle’s blackened hulk to extract charred human remains while eight wounded survivors were rushed to hospital.
In another bombing, 19 day-labourers waiting to be hired for work were hurt in central Baghdad, the official said.
The carnage could have been worse as police discovered a nearby car packed with explosives which had failed to go off.
In other violence on Monday, five Iraqis were killed when their truck convoy carrying building materials came under rocket and automatic weapons fire north of Baghdad, police in the northern city of Tikrit said.
A group of 15 cars attacked the convoy with firearms and rocket-propelled grenades, killing five of the nine truck drivers, wounding three more and destroying six heavyweight vehicles.
A bomb attack also targeted a restaurant in the centre of the northern city of Mosul, killing five, including one policeman and wounding 21, of whom 14 were policemen, medical and security sources said.
Police said that one man who had been seen eating his breakfast placed a bag underneath the counter before walking out.