The tribunal's head judge, Obaidul Hassan, issued the order against Forkan Mollick, saying he committed the crimes in southern Patuakhali district.
The man worked at a local office of the Jamaat-e-Islami party, Bangladesh's largest Islamist party, which had organized people to fight against the independence struggle.
He was a low-ranking activist of another party, the Muslim League, in 1971.
After Thursday's verdict, Mollick shouted from inside a prison van that he was innocent as police took him away.
"I am innocent, I was their employee, that's why I have been punished," he said, referring to Jamaat-e-Islami.
Bangladesh says Pakistani soldiers, aided by local collaborators, killed 3 million people and raped 200,000 women during the war in East Pakistan, which is now Bangladesh.
The defense plans to appeal the verdict, which is part of a series of decisions by two separate tribunals set up by Prime Minister Sheikh Hasina in 2010.
More than 15 people, mostly leaders of Jamaat-e-Islami party, have been convicted of war crimes.
The party has rejected the verdicts, saying it is politically motivated, but authorities have denied that allegation.
Related story
Bangladesh sentences seven to death for 2016 cafe attack
_20191222200001.jpg)
