Syed Mohammad Qaisar, 73, formed a group named "Qaisar Bahini" with 500 to 700 men, who committed crimes against humanity in Habiganj and Brahmanbaria during the war.
He was also a commander of the Rajakars (an auxiliary group of then Pakistani army) in the districts, prosecution was quoted as saying by The Daily Star.
Qaisar, a former Muslim League leader and the state minister for Agriculture during the dictatorship of H M Ershad, was arrested in May last year.
Qaisar pleaded not guilty after the court read out the charges against him.