At least 14 people have been killed in suicide car bomb attacks on police in Baghdad and Kurdish militiamen in the northern Iraqi city of Mosul.
The Baghdad blast was heard several kilometres away
Two cars exploded at the entry of Baghdad's Green Zone at around 0930 (0630GMT), killing seven people.
More than 50 people were wounded in the attack.
Later, a suicide bomber blew up his car beside a bus carrying the Kurdish militiamen linked to one of the two main Kurdish parties in north Iraq.
In other developments:
- Two US soldiers are killed in a roadside bomb attack in east Baghdad on Saturday and five are injured
- A US soldier dies and another is wounded when a bomb targets a US convoy near the town of Baquba, north of Baghdad
- Another two US soldiers were killed and five wounded in a car bombing at the Trebil border crossing between Jordan and Iraq on Friday
- The British Black Watch battle group pull out of Camp Dogwood near Baghdad and return to their base in Basra in the south of Iraq
- Police in Germany arrest a Lebanese citizen in connection with an alleged plot to attack the Iraqi Interim Prime Minister, Iyad Allawi, during a visit to Berlin this week.
The top American commander in the region, General John Abizaid, expressed concern about the ability of Iraqi forces to cope.
He said they did not have the training or experience to do the job without extra American help.
Witnesses said they saw two vehicle being driven towards the Salhiyah police station in Baghdad on Saturday morning.
"I was on guard duty in front of the building," said 27-year-old policeman Adel Abdel Sadek, whose face was covered in cuts.
"I remember that a car wanted to get into the police station and we refused, and then the explosion happened," he was quoted by AFP news agency as saying.
Even by Baghdad standards, the blasts were very powerful, the BBC's Peter Greste reports from the city. They blew out a window of his office several kilometres away.
The force of the explosion blew off the facade to the station and tossed another car onto the roof of a two-storey building opposite.
The police station is next to a checkpoint leading into the heavily-fortified Green Zone, which houses Iraq's interim government and foreign missions.
US embassy spokesman Bob Callahan said no US and coalition staff had been killed or wounded.
In the northern city of Mosul, a suicide bomber pulled his explosive-laden vehicle alongside a bus bringing the Kurdish peshmerga fighters into the city.
The militiamen belonged to the Patriotic Union of Kurdistan (PUK), said Saadi Ahmed, a PUK official.
The militiamen were being brought in from the mainly Kurdish city of Irbil in order to protect PUK offices in Mosul.
The PUK backed the US-led war against Saddam Hussein and is part of the interim government.
Iraqi police and security forces are frequent targets of insurgents fighting US-led forces and the interim government.