The ombudsman is warning prisons have not adjusted their approach since Covid-19 lockdowns, with some prisoners left in isolation for 23 hours a day.
Chief ombudsman Peter Boshier appeared before MPs at select committee on Thursday morning with four reports on prisons.
He presented four reports about prisons to the select committee this morning, and said there was an unacceptable culture of containment in many prisons - with situations of no visits, meaningful human contact or rehabilitation - which had continued since the pandemic response.
"One might say 'well, everything's changed' - we've been able to put that to the test to quite some extent," he said.
"Corrections is glacial. Getting change within this organisation is like pushing a barrel of concrete uphill and when I talk about Auckland prison I think you'll see what I mean."
One of the four reports was about nine prisons, and showed lockdowns increased, rehabilitation programmes decreased, and prison visits became virtually non-existent.
He pointed to units at the maximum-security Auckland prison as particularly problematic, and said Corrections had "not done a lot since Covid to improve the situation".
Some prisoners being held there had been in segregation for over a year, he said, and were alone for 23 of 24 hours a day.
"It's graphic. Can you imagine a situation where you are in your cell - just you - for 23 of the 24 hours a day and where you don't actually talk to anyone in the course of that day?
"Your right to exercise is either in a little exercise yard of your cell or it's in a exercise yard but prisoners go in there pretty much one at a time because they don't feel they can manage this satisfactorily.
"I think that mere containment of a prisoner with no meaningful human contact and no real rehabilitation programmes is just not acceptable, and I think what we must do in our prisons is have reasonable standards of care - we're falling short of those.
"We're just really managing and containing prisoners rather than giving them programmes and a meaningful day by day existence."
The new build at Auckland prison meant it was much more transactional, he said, with prisoners no longer interacting with people as they were moved between areas, and meals were simply handed over.
"We've regressed in our care at this high end," he said. "My staff put it to me in this way, that this is like almost a storage unit, a people storage unit. It is containment and management.
"Covid justified an amount of restriction for perfectly understandable reasons. What I'm saying to you is that now I do not see much change. I still see - not just in Auckland prison but in some others - a restrictive regime of lockup hours and also non-visits."
He said it included a continuation of policies that meant a lack of visits to prisoners.
"I can understand that in Auckland in the maximum setting there's a need for huge care, I understand that - that's where some of our high-end dangerous prisoners are housed. But we've found in a number of prisons across the country post-Covid, Corrections have still not reintroduced proper visitation rights for families and prisoners."
Pepper spray was also continuing to be used "in a way which we find offensive", he said.
Finally, he said he saw no sign of efforts to rehabilitate.
"If we've regressed to the point that we're saying rehabilitation no longer matters because we haven't got the staff and it doesn't work for us, I think we're in a very bad state in our prison system in New Zealand."
He said this was pushing the boundaries of breaching international expectations and prisoner rights, they were being denied the right to a certain amount of human contact, and he feared for the effects on prisoners' mental health.
"Disappointing" was an understatement, he said, especially considering Ombudsmens' reports had raised these concerns before, going back four years ago to 2020.
They normally saw evidence of agencies implementing changes as a result of those reports, but "we just don't see it with Corrections".
Corrections had previously said staff shortages were partly to blame, but Boshier said that was being used as an excuse.
"I don't just accept it's physical limitations of staff numbers, I think we've dumbed down in what we're prepared to do and how energetic we're prepared to be.
"If I'm to be cynical, they've blamed staff shortages but in fact there is a bit of a culture now embedded that a lot of these things will be done in minimalist fashion, and I'm afraid that's the way we see it.
"Why are we locking these people up for 23 hours a day: Is the answer you haven't got enough staff or does it just suit you."
He saw little evidence of a culture at many prisons and at Corrections of wanting to make changes, which worried him.
"How do you change an organisation? Well, good concerted leadership; a feeling by those who are working there that they want to achieve change and they want to do things," he told RNZ.
"I think it's very much a will to see what we're saying in our reports and want to achieve change ... I don't see at the moment a huge will to want to change."
He said the situation was pushing the boundaries of breaching international expectations and prisoner rights, they were being denied the right to a certain amount of human contact, and he feared for the effects on prisoners' mental health.
It was not all bad news, however. Another of the ombudsman's reports focused on Tongariro prison, a minimum-security prison the ombudsman said was operating well, which others could learn from.
"It's an exemplar ... Tongariro is doing the things that you'd want it to. It's got a high Māori inmate population: they're doing good things with iwi, good things with culture."
The leadership at Corrections could do much more to promote a the kind of culture needed to achieve positive change, he said.
RNZ has sought comment from Corrections.