Bush set to announce withdrawal of 8,000 troops from Iraq.
Attack on police station leaves at least 40 people wounded.
The Dujail attack was one of the deadliest in Iraq in recent months and comes at a time when the violence in Iraq is at a four-year low.
The last major suicide attack occurred on August 26, when a bomber thwarted a security checkpoint in Jalawla, a police recruiting centre, and blew himself up, killing at least 25 people.
Dujail is a mainly Shia town in the Sunni province of Salaheddin, north of Baghdad.