A suicide bomber has driven a car bomb into a police station, killing 13 people and wounding 15 in the town of Hibhib, north of Baghdad near Baquba, police said.
A police source said the attacker struck a queue of recruits lined up to join the police force in the town on Thursday. The dead included five police and eight civilians.
The attack came a day after a series of high-toll explosions in Baghdad, in which suicide bombers killed more than 70 people.
Lieutenant-Colonel Ibrahim Khalil, a provincial police officer, said that five policemen were killed in the blast.
Hibhib is in Diyala province, which has been the focus of a US offensive for the past two months after Washington dispatched extra troops to Iraq.
The US has said Diyala province has seen an influx of al-Qaeda fighters driven out of Baghdad and western Anbar province as a result of the US fighting and disagreements with local tribes.
Political divisions
Leaders of Iraq's main political groups are due to meet in the coming days to try to reform their coalition, which was set up last year.
The coalition has so far failed in its aim to reduce violence and agree on reconciliatory laws.
The office of Nuri al-Maliki, the Iraqi prime minister, said he would remain in permanent contact with the Sunni Accordance Front, despite the group's decision to pull its six ministers out of the government on Wednesday.
The front said it was quitting al-Maliki's coalition because he had failed to meet its demands, including giving the Sunni bloc a greater share in security matters.
The political bloc of Muqtada al-Sadr, a populist Shia leader, quit the government in April.