A suicide bomber driving an ambulance has killed up to 15 people and wounded more than 50 in an attack on an Iraqi police training centre in volatile Diyala province.
Suspected Sunni insurgents and Shia militia have stepped up attacks in recent months on Iraqi policemen and soldiers, seeking to undermine faith in the security forces before a full US military withdrawal by the end of this year.
Samira al-Shibli, a spokeswoman for the provincial governor said 15 people were killed and 52 wounded in the attack in the city of Baquba, 65km northeast of Baghdad.
One police source said there were two attackers. One of them shot dead three security guards at the gates of the training centre, opening the way for a second assailant to drive the ambulance in.
The blast caused the collapse of part of the three-storey building, where offices for different departments of Iraqi police and security are located.
"I can see hands and legs of dead policemen sticking out from under the rubble," said a policeman at the blast site.
Today's attack was the second by a suicide bomber in two days on Iraqi security forces. At least 49 people were killed in former dictator Saddam Hussein's hometown of Tikrit yesterday when a suicide bomber attacked a line of police recruits.
In a separate incident today, a suicide car bomber killed two Shia pilgrims and wounded 16 on a road between Baquba and Baghdad.
Attacks against Shias are expected to rise ahead of the religious event of Arbain, which culminates next week. Arbain marks a 40-day mourning period for Imam Hussein, a grandson of the Prophet Mohammad who was killed at the battle of Kerbala in the 7th century.
That was the bloodiest attack in Iraq since Prime Minister Nuri al-Maliki won support in December for his reappointment, ending a nine-month stalemate that followed a March election.
Overall violence has fallen sharply since 2006-07 peak of the sectarian slaughter between once dominant Sunnis and majority Shias triggered after the 2003 US-led invasion.
But Sunni Islamist groups like al-Qaeda still battle Iraqi security forces, particularly in ethnically mixed Diyala, Baghdad and the turbulent northern province of Nineveh, and target the less visible US forces whenever they can.
Analysts said recent attacks are probably not related to the formation of the new Shia-led government, which includes the Sunni-backed Iraqiya bloc.