A prisoner advocacy group has highlighted the plight of a group of inmates in a unit at Auckland Prison who are not being granted access to a toilet during the day.
Christine McCarthy from the Howard League for Penal Reform said the issue was raised in a letter from a prisoner held in the Auckland jail.
"They're put in a day-room ... it sounds like for about three or four hours in the morning and then they swap over with the prisoners in the yard ...
"If they need to go to the toilet there's nowhere to go to the toilet so they're urinating in bottles, they're urinating in the sinks they wash their dishes in. It's a really unacceptable situation."
Ms McCarthy is unsure how long that has been happening, but said access to a toilet is one of the most basic necessities for prisoners, along with meals.
She said the lack of toileting opportunities again highlights the inhumane conditions in New Zealand's jails and follows a scathing Ombudsman's report on conditions at Auckland South prison.
"It appears inmates are being subjected to extra [hardship] because Corrections does not have enough officers on-site to provide suitable care."
However the Corrections Department is denying the allegation.
In a written statement, the director of Auckland Prison, Andy Langley, said an issue relating to toilet use arose when the new maximum security facility first opened last October, but it was quickly resolved.
"There was a very small number of incidents where prisoners urinated into milk cartons and a sink in the day room. The prisoners were told this behaviour was unacceptable and were instructed to stop.
"Prisoners have been told before - and reminded again since - that if they need to use a toilet while in the day room, they should alert staff who would take them to their cell toilet and then return them to the day room.
"Our staff work hard to facilitate these requests as quickly as possible while ensuring the safety and security of other prisoners and staff in the unit is upheld at all times."
Mr Langley said there was one further incident last week involving a new prisoner, and as a result information on accessing toilets is now included in prisoners' induction packs.