New Zealand's record on the treatment of prisoners is criticised in Amnesty International's latest world report on Human Rights.
The report, which documents the state of human rights in 159 countries over the past year, says New Zealand is contravening international standards by allowing double-bunking in prisons.
Amnesty International's New Zealand chief executive, Patrick Holmes, says under the United Nations guiding principles on the treatment of prisoners the sharing of cells should not be allowed.
However, he says little can be done about it because the standard is non-binding and cannot be enforced.
Mr Holmes says double-bunking erodes prisoner rights.