A report into New Zealand's only maximum security prison reveals myriad problems and shows it is failing on promises to boost rehabilitation.

Chief Ombudsman Peter Boshier inspected Auckland Prison at Paremoremo unannounced and found "a number of matters that were deeply concerning" - including that prisoners were being locked in cells for 22 to 23 hours a day, despite new units opening to aid rehabilitation.

In a report released today on his visit, Boshier said he found a number of significantly concerning issues, including two breaches of the United Nations Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment.

"We are not achieving what we are meant to in terms of our obligations. That's why I'm being fairly clear in my criticism.

"There appears to be a serious and unacceptable lack of ventilation, compounded by impending summer heat, in the low and high security units.

"Pepper spraying a prisoner, after he followed officers' orders, was unwarranted and amounted to cruel treatment.

"Furthermore, staff had failed to accurately report the incident which was captured on CCTV. This is concerning as staff receive Control and Restraint training."

In a detailed recounting of what happened in the pepper-spraying incident, Boshier told Checkpoint footage showed that a prisoner had tampered with a sprinkler, retreated to the rear of his cell and complied when officers asked him get down.

"He was then pepper-sprayed. The prison officers wrote up a report on this and understated and minimalised what had happened."

Boshier said that was unacceptable.

Chief Ombudsman Peter Boshier.

"I would like to see it routine that when a prison officer is beginning an interaction with a prisoner, the [body] camera is turned on, so that the important beginning part of it is captured. Let's hope that the use of body cameras in this setting becomes routine and unexceptional."

Spending long periods in segregation meant prisoners had few chances to display good behaviour, he said.

"I consider such long stays in directed segregation inappropriate and well in excess of the 15 days set out in the Nelson Mandela Rules.

"I can't see how one is going to try and normalise a prisoner in that setting when you are in that artificial and pretty oppressive situation for all of that time."

A survey of prisoners revealed that 35 per cent said they had been assaulted, and 13 per cent sexually assaulted in the prison.

"A high number of prisoners sought voluntary segregation mostly because of gang issues, bullying, stand-overs, and a fear for personal safety."

Boshier told Checkpoint the report was "disappointing" and the prison was "not really achieving goals it was set out for".

"So big challenges ahead, strong leadership needed.

He said the maximum security units on the Paremoremo site, opened in July 2018, were meant to help rehabilitate prisoners but they were unable to access rehabilitation and education programmes.

He said there were privacy issues, with CCTV in all areas of the Intervention Support Unit, including the toilets.

Staffing problems were leading to missed opportunities for prisoners, he said, including appointments with the Parole Board, Work and Income and their case managers.

"Staff vacancies and unplanned leave, particularly in the high and maximum security units, also meant that both prisoner and staff safety could be compromised."

More than a third of staff had less than two years' experience as well, meaning relationships with prisoners were "largely transactional".

"It's only after a period of time I would suggest as a prison officer that you learn how to manage and how to do it in a holistic way.

"I think you can look to Covid-19 and the lockdown as the start of prison guards' availability being reduced and a bigger lockdown regime being introduced, because that was practical and pragmatic - unfortunately, I think that's just continued."

On the other hand, Boshier noted there were some good practices at the prison - like no double-bunking.

The Chief Ombudsman made 37 recommendations, of which the Department of Corrections accepted 33 and partially accepted four.

Corrections told Boshier that it had been implementing his recommendations since the inspection earlier this year, including appointing more staff.

Boshier visited the prison on December 1 to check on progress.

"In my view, the Department of Corrections' intention to shift its operating model away from containing difficult prisoners has yet to be realised. I expect to see significant improvements in the conditions of maximum security prisoners."

Text By RNZ