The bomber entered the mosque compound during a reconciliation meal between Shia and Sunni held while breaking the daily fast during the month of Ramadan. At least one other senior officer died alongside the police chief.

Baquba is the capital of Diyala province, where US and Iraqi operations have recently targeted militants.

Earlier, six people were killed in a suicide truck bombing at a security checkpoint near the city of Mosul.

Eyewitnesses said the Baquba bomber entered the compound while most of the victims were in the mosque courtyard washing their hands or sipping tea during the meal, known as the Iftar.

Security guards approached him but he set off his device when they challenged him, police spokesman Maj Salah al-Jurani said.

The governor of Diyala, thought to be among the wounded, may have been the intended target, the spokesman added.