A Buddhist inmate accused of informing on other prisoners by dropping letters in prison 'dob boxes' is in a court fight to prove he's not a snitch.

Robert Sloan was moved to a restrictive high-security unit at Barwon Prison because authorities believed his life was at risk after he allegedly wrote letters about planned hits on him and other prisoners.

Inside Barwon Prison. Credit:Angela Wylie

Prison "dob boxes" are an anonymous tip-off system where inmates can alert prison authorities to security threats inside units, but those who use them are considered "dogs" and are targeted by other prisoners.

Sloan denies he snitched, wants to be returned to his former unit and has taken his fight to the Victorian Civil and Administrative Tribunal to have the letters released.