A Burmese student leader, Thet Win Aung, has died in prison.
Thet Win Aung's father Win Maung told Burmese media DVB that officials notified him of the death Monday evening.
He speculated that Thet Win Aung might have had a heart attack after hearing news that his brother, Pyone Cho also a student leader, had recently been arrested.
Amnesty International said it is deeply concerned by Thet Win Aung's death in Mandalay Prison and called on authorities to investigate the circumstances surrounding it.
Thet Win Aung had been imprisoned since 1998 for organizing student protests. Amnesty says he was badly tortured during his imprisonment and suffered from a variety of health problems.
The rights group says it fears for the health of prisoners in Burma, particularly for those debilitated by years of imprisonment and ill treatment.