Amnesty International is calling on the Fiji interim government to address allegations of torture inside Fiji prisons.
This follows last September's escape and recapture of five inmates from Naboro Prison.
Amnesty International New Zealand's chief executive Grant Bayldon, says reliable research claims the men were then beaten, one so badly his leg was later had to be amputated.
"We've sent the Prime Minister an open letter, and we've asked him to address the allegations. We've asked for an independent investigation urgently, and for those who are responsible for torture to be brought to justice. The open letter, we sent to Commodore Bainimarama several days ago, before it was published, to give him the opportunity to respond. We haven't had a response to date."
Grant Bayldon says the information has been shared with the New Zealand government, and Amnesty is asking it to raise the issue with Fiji.
The Fiji regime has said it is investigating the circumstances of their recapture.