At least 23 people have been killed in several attacks targeting security forces in the Iraqi capital, Baghdad.
Police were attacked as they sat in their cars
Suicide bombings at an army recruitment centre and outside an interior ministry official's home left 13 National Guards and a police guard dead.
Elsewhere, gunmen killed nine police officers in attacks on patrol cars.
The attacks come amid a wave of violence that saw a suicide bomber kill dozens of people in the Kurdish city of Irbil on Wednesday.
That attack was the bloodiest in the Kurdish region since the war.
It came a day after a new but incomplete Iraqi government was sworn in.
Members of Iraq's police force and police volunteers are frequently targeted by insurgents, who view them as collaborators with US-led forces.
MAJOR ATTACKS SINCE JAN POLL
5 May: At least 23 people die in wave of attacks in Baghdad
4 May: At least 50 people killed in suicide attack on police recruits in Irbil
29 April: At least 29 people killed in wave of car bomb attacks on Iraqi security forces
10 March: 47 people killed by suicide bomber at Shia funeral in Mosul
28 February: Massive car bomb kills 125 people in Hilla
19 February: Suicide bombers kill 30 people during Shia Ashura celebrations
18 February: Around 29 people die in attacks in Baghdad and Iskandariya
7 February: Attacks on security forces kill at least 25 people in Mosul and Baquba
The attack on the recruitment centre, at the former Muthanna airfield in central Baghdad, happened at about 0800 local time (0400GMT). As well as the 13 fatalities, several people were wounded.
The bomber reportedly walked into the centre before detonating explosives strapped to his body.
The base, not far from Baghdad's so-called Green Zone where the parliament is based, has been targeted several times by suicide bombers.
Hours earlier, gunmen ambushed police sitting in their cars at two junctions in different parts of the city, killing nine and setting fire to their vehicles.
The senior interior ministry official's home was attacked by a suicide car bomber, who killed a police guard.
Another suicide car bomb was directed at an US military patrol. A Humvee vehicle was reported to have been set on fire.
Although it was sworn in on Tuesday, the new Iraqi government has still not completed its own formation by announcing an agreement with Sunni groups on how to represent their community, in which the insurgency is rooted.
The BBC's Jim Muir in Baghdad says many Iraqis are blaming the delay for the apparently unstoppable wave of violence.
Planning Minister Barham Saleh told the BBC that agreement had now been reached on all but the defence minister's post, and he expected an announcement at any time.
Meanwhile, Bulgaria has become the latest country to decide to withdraw its troops from Iraq.
Its parliament voted to pull out the 450 troops by the end of the year.
Eight Bulgarian soldiers have been killed while serving in Iraq.