At least 23 people have been killed during a series of insurgent attacks on the security forces across Iraq.
Sixteen people were injured in the Samarra bombing
Eleven died during bomb attacks outside the home of a policeman in the restive northern city of Samarra.
In another northern city, Mosul, at least four policemen died in a suicide car bombing.
The blasts followed the discovery of the bodies of eight policemen who died in an attack by gunmen in the western city of Ramadi.
There were also reports of clashes between US-backed Iraqi forces and insurgents at Tal Afar, near Mosul.
The attack in Samarra began with several carloads of armed men occupying a road outside the house.
They opened the way for a suicide bomber to drive up and detonate his explosives, killing nine civilians and wounded 16 others.
Two attackers were killed, apparently while planting a second bomb intended to kill emergency services workers arriving at the scene.
The officer - a member of an elite police commando unit - was not injured.
In the Mosul attack, a suicide attacker rammed his vehicle into an Iraqi police patrol on a bridge in the south-west of the city.
The eight policemen who died in Ramadi had been manning a checkpoint on the road between the western city of Ramadi and the Syrian border.
They were apparently ambushed.
'Enemies of freedom'
On Friday, US President George W Bush and the Iraqi Prime Minister, Ibrahim Jaafari, spoke of their determination to crush the insurgency.
In his weekly radio address on Saturday, Mr Bush said: "The images we see on television are a grim reminder that the enemies of freedom in Iraq are ruthless killers with no regard for human life.
"Our military strategy is clear: we will train Iraqi security forces so they can defend their freedom and protect their people and then our troops will return home with the honour they have earned.
"The political track of our strategy is to continue helping Iraqis build the institutions of a stable democracy."