Major General Qassim al-Moussawi said the bomber set off his explosives vest in the police chief`s office at the station in Tarmiya, 25 km (15 miles) north of Baghdad.
"This is the initial toll and we expect it to rise," Moussawi told Reuters.
He said the 12 wounded included nine policemen and three civilians.
An Interior Ministry source put the toll at two killed and 17 wounded, including nine policemen.
Attacks against Iraqi security forces have been increasing as the country`s army and police prepare to take total responsibility for security ahead of a full withdrawal of U.S. troops by December, more than eight years after the invasion.
Insurgents launched at least eight attacks on police in Baghdad and northern Mosul on Wednesday, using a combination of guns and explosives.
Bombings and killings remain a daily occurrence in Iraq as security forces fight a stubborn insurgency, although overall violence has dropped since the height of sectarian fighting in 2006-7. (*)
Editor: Kunto Wibisono
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