At least 40 people have been killed in four car bomb attacks and raids on police stations in the Iraqi city of Samarra.
More than 60 other people have been wounded.
The attackers targeted the town hall and a security checkpoint in Samarra, around 60 miles north of Baghdad.
In one attack, a suicide bomber rammed a car into a police station, detonating the device, and killing ten officers.
In the first three bomb explosions, 23 people including nine policemen were killed.
In Ramadi, 70 miles west of Baghdad, 20 US marines are reported to have been injured in an attack on their convoy.
And on the main airport road in Baghdad, three American soldiers were wounded in a suicide car bombing.
Militant group claims Baghdad bombing
In a separate development, a group led by al-Qaeda ally, Abu Musab al-Zarqawi, has claimed responsibility for a suicide car bombing which killed three British troops in Baghdad, two days ago.
In a statement posted on an Islamist website, the group said it would strike the infidels with an iron fist.
The three soldiers - from the Black Watch regiment - and an Iraqi translator were killed when a suicide bomber attacked a checkpoint they were manning.
Eight other British soldiers were wounded.
