The study adds to years of warnings by experts that the country's prisons have become a jihadis training ground.
The research conducted by psychologists from the University of Indonesia found that prison staff lack the ability to identify high-risk inmates who could recruit others because they're given limited information and little specialist training.
Indonesia, the world's most populous Muslim nation, has arrested and imprisoned hundreds of militants in the crackdown that followed the 2002 Bali bombings.