A car bomb exploded outside the Rafidain state-run bank in the centre of Tikrit and a suicide bomber blew himself up as emergency workers arrived on the scene, police said.
"We have 12 people killed and 28 more wounded," said Raed Ibrahim, head of the provincial health department. "Ambulances and civilian cars are still bringing in the wounded."
Tikrit, the hometown of former dictator Saddam Hussein, is dominated by Sunni Muslims and suspected militants tied to al Qaeda have carried out frequent attacks in the town this year.
Violence in Iraq has dropped sharply from the height of sectarian killing in 2006-2007, but insurgents and militias still carry out daily attacks and assassinations in an attempt to undermine the government.
Local police and soldiers are increasingly targeted by insurgents and militias.
More than eight years after the US-led invasion that toppled Saddam, the last American troops are due to leave by the end of this year. Iraqi forces say they can contain internal threats but acknowledge they need more training to plug capability gaps.
COMMENTS
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ