A prison reform group wants the Ombudsman to investigate what it says is a deterioration in prison living standards.
Figures released to Radio New Zealand show the Department of Corrections has spent $994,840 over the past year housing inmates in police cells.
Kim Workman from the group Rethinking Crime and Punishment says there has been a marked decline in prisoners' conditions.
He says as well as the use of police cells, inmates are spending more time in their cells in prison, there has been an increase in double bunking and a deterioration of prison mental health services.
Mr Workman says the Obudsman should review whether United Nations' requirements are being breached.
Tighter legal aid rules have led to a drop in the number of lawyers available to represent prisoners at parole board hearings, Mr Workman says.
He says many lawyers who represent parolees are no longer eligible to receive legal aid.
Mr Workman says many inmates are inarticulate and incapable of presenting themselves at parole board hearings.
He says the situation is a denial of due process as prisoners have no assurances the judicial process is being properly followed at the hearings.