"Our forces captured Jassem al-Khafadji who says he has kidnapped and assassinated 11 men and five women," Defence Ministry spokesman General Mohammed al-Askari told reporters.

"He then led us to the place where he had buried them."

Khafadji is among some 500 people the military says have been arrested since the launch on July 29 of a major operation in Diyala province aimed at flushing out Al-Qaeda fighters who control vast swathes of the countryside.

The operation is being carried out by the Iraqi army, supported by the US military.

Fed by the Euphrates and Diyala rivers, Diyala was once the granary of Iraq and the country's orange capital with its lush orchards, but its multi-ethnic population has proven one of the most dangerous to control.