More than 50 people have died in a wave of attacks across Iraq, including 20 killed when a suicide bomber struck a Baghdad police station, officials said.
The blast at the police station was heard across the capital
The bomber drove a truck up to the station, detonating explosives which brought down half of the building.
The violence came as US and Iraqi forces continued their security push in the Iraqi capital to try to curb insurgent and sectarian violence.
Among other attacks, a suicide bomber killed 10 people in northwest Iraq.
On Saturday morning, an explosion reverberated across the Iraqi capital and a plume of black smoke rose into the sky.
The target of the attack was a police station in the mainly Sunni district of Doura in southern Baghdad.
Most of those killed were police officers. A further 26 people were injured in the blast.
A police officer who witnessed the attack told the Associated Press news agency that the bomber was able to take advantage of building work being done at the police station, getting round security by hiding his explosives under bricks.
"We were very cautious, but this time we were taken by surprise," Police Cpl Hussam Ali said. "The insurgents are inventing new methods to hurt us."
Another suicide truck bomber targeted a Shia mosque in Iskandariya, south of Baghdad, killing eight people.
In Talafar, in northwest Iraq some 75km (50 miles) from Syria, a suicide bomber blew himself up in a market, killing 10 people.
Three suicide attacks on one of the main roads from the Syrian border left 11 people dead and 25 injured.
The Syria-Iraq route is regarded as the easiest way into Iraq for would-be suicide bombers, but the Syrian authorities vehemently contest that, says the BBC's Hugh Sykes, in Baghdad.
Among other reported violent incidents in Iraq on Saturday:
- Police found 12 bodies in the city of Falluja, west of Baghdad
- Four Iraqi soldiers were killed when a roadside bomb exploded in Falluja, Iraqi police told the AFP news agency
- A truck bomb in the town of Haswa, south of Baghdad, exploded, leaving at four people dead
- The US military said it called in air strikes and killed three suspected insurgents in the Rutba area near the Jordanian border. A fourth suspect blew himself up
In the Iraqi capital, a security operation by thousands of US and Iraqi forces continued to try to stem the bloodshed.
The security sweep in Baghdad began last month
The operation has reduced the number of sectarian shootings but stopping the daily car bombings has proved more difficult, correspondents say.
The troops set up checkpoints and sealed off a large part of central Baghdad.
All vehicles and pedestrians were stopped from entering the Karrada district, next to the fortified international zone where the Iraqi government headquarters, diplomats and much of the US military is based.
A double bombing just outside the zone on Friday injured one of Iraq's deputy prime ministers, Salam Zaubai, and left nine people dead.
Mr Zaubai was said to be in a stable condition after he had surgery to remove shrapnel.