At least 25 people have been killed in Iraq in the latest series of attacks by insurgents.
Ramadi has been the scene of frequent clashes
A car bomb outside a police academy killed at least 15 people during a graduation ceremony in Hilla, south of Baghdad, on Wednesday.
Earlier in the day, six died in another suicide attack in Baquba. Four people were also killed in a clash in Ramadi.
US and Iraqi forces have been facing an increase in insurgent violence ahead of Iraqi elections planned for 30 January.
The attacks came after interim Iraqi Prime Minister Iyad Allawi reaffirmed that holding the poll on time was essential.
Many of those killed in the attack on the Hilla police academy were officers, police say.
A number of others were wounded in the bombing.
In the Baquba incident, north-east of Baghdad, at least six police were killed and 13 wounded when a suicide bomber targeted a security checkpoint.
Earlier, at least four civilians died and two more were injured when they were caught up in fighting between US forces and insurgents in the Sunni town of Ramadi, west of Baghdad.
A battle broke out when insurgents detonated a roadside bomb as a US convoy drove past.
Shortly before the Hilla explosion, Mr Allawi had insisted that elections must take place on time.
"The violence, terrorists and the outlaws will not be allowed to stop the political process and destroy the country," he said.
Iraqi interior ministry figures released on Wednesday revealed that 1,300 police died in attacks during the last four months of the year, AFP reported.
On Tuesday, a suicide bomber killed 11 in an attack on police headquarters in Baghdad.