At least 50 people have been killed in a series of apparently co-ordinated bomb attacks across Iraq.
The deadliest killed 19 people in the southern city of Kut. Several blasts hit Baghdad, including a suicide bombing in which 15 died.
There were also attacks in other major cities. Officials blame al-Qaeda.
Correspondents say the violence highlights fears about the stability of Iraq ahead of the formal end of US combat operations next week.
Almost all of Wednesday's attacks targeted security forces.
In Baghdad, the suicide car bomb hit a police station in the Qahira district in the north-east of the city killing 15 people, most of them police.
Police and hospital officials said 58 people were wounded in the explosion, which left a crater 3m (10ft) wide and caused houses to collapse, trapping people inside.
"We woke up to the sound of this powerful explosion that shook the area," resident Abu Ahmed, 35, told the Associated Press news agency.
"I searched for victims in the destroyed houses, and evacuated seven dead children and some women."
Elsewhere in the capital, smaller explosions killed at least four people and injured many others.
In Kut, 160km (100 miles) south-east of Baghdad, a suicide bomber blew up a car outside a police station and the provincial government's headquarters.
At least 19 people were killed and 90 wounded.
In other incidents:
- in Kirkuk, a car bomb killed one person and injured eight
- in Falluja, a soldier was killed and 10 people injured when a suicide bomber drove into an Iraqi army convoy
- in Tikrit, a roadside bomb killed a policeman and wounded another
- in Mosul, a gunman killed one soldier and a car bomb killed four civilians
- in Basra, a car exploded as police towed it from a parking lot, killing one person and injuring eight
- in Ramadi, a car exploded as two alleged bombers were working on it, while a second car exploded about 1km away, killing at least two
- in Karbala, a suicide car bomb exploded at police checkpoint at the entrance to police station, injuring 30 people
The Reuters news agency reported other explosions in Dujail, Balad Ruz and Samarra, but these could not be confirmed.
No group has said it carried out the attacks, but the BBC's Hugh Sykes in Baghdad says the Islamic State of Iraq, a branch of al-Qaeda, may be behind some of them.
US military spokesman Maj Gen Stephen Lanza called the attacks "desperate attempts" by al-Qaeda to undermine faith in the Iraqi security forces.
Iraqi security spokesman Maj Gen Qassim al-Moussawi also blamed al-Qaeda, and warned of more attacks as US troops end combat operations on 31 August.
"By mobilising all its capabilities, the enemy is trying to escalate the terrorist attacks during this coming period," he said. "We have plans to face those terrorist attacks."
Violence in Iraq is down from the peak seen during the sectarian conflict in 2006-2007, although the number of civilian deaths rose sharply in July.
Almost daily attacks on Iraqi forces and traffic police in Baghdad and Anbar province, west of the capital, killed more than 85 people in the first three weeks of August.
On Tuesday, the US military said the number of US troops in Iraq had fallen to 49,700, as Washington prepares for its 31 August deadline to end combat operations.
The remaining US troops will continue in Iraq until the end of 2011 to advise Iraqi forces and protect US interests.
They will be armed, but will use their weapons only in self-defence or at the request of the Iraqi government, and will work on training Iraqi troops and helping with counter-terrorism operations, the US military said.
Iraq's top army officer recently questioned the timing of the pull-out, saying the country's military may not be ready to take control for another decade.
Meanwhile, Iraqi politics has remained deadlocked five months after national elections, with no new government yet in place.