Amnesty International says Indonesian authorities must immediately investigate the torture of Papuan prisoner Ferdinand Pakage, who is being detained at Abepura prison in Indonesia's Papua.
The watchdog says prison officers beat Mr Pakage on 22 September causing serious injuries to his hands and legs.
It says that according to media reports, his left eye was also bleeding profusely when he was removed from solitary confinement and taken to the hospital for medical attention.
The beatings were witnessed by other prisoners.
Amnesty says those responsible for the torture must be held accountable.
It says Mr Pakage was sentenced to 15 years jail after an unfair trial for his alleged involvement in the violence in Abepura in March of 2006.
He and others were subject to torture and other ill-treatment during interrogation in order to force them to confess.