A union representing frontline corrections officers says even officers did not like working at the the high security area of Waikeria Prison, where inmates have been on a riot for a third day.
Disorder started on Tuesday, when fires were set in an exercise yard, causing massive damage across a high-security area.
The Department of Corrections says 21 prisoners were involved - four surrendered but 17 are still refusing to co-operate.
It is New Zealand's biggest prison riot in seven years - and it started with a tip.
Corrections received a call on Tuesday at lunchtime, telling them a riot might soon break out at Waikeria Prison, near Te Awamutu.
Staff took a look and could not find any issues. But Corrections chief executive Jeremy Lightfoot said matters escalated quickly.
"A short time later, prisoners in an exercise yard in the top jail, the high security part of the site, lit several small fires," he told reporters at a press conference yesterday.
After some time, prisoners got on to the roof and could access other units, letting other prisoners out of their cells.
Twenty-one prisoners started causing chaos and massive fire damage.
Sources inside Waikeria say the men are protesting about dilapidated conditions, cramped cells, a lack of basic supplies and the implementation of a Corrections strategy for Māori.
That strategy is meant to reduce the over-representation of Māori in New Zealand prisons.
But one source said: "We hear about this Hokai Rangi strategy but we don't see it. There is no programme. There is no rehabilitation. It's lock us up, put you in a yard full of gang members and then let you out. And they expect us to change."
Waikeria is one of the country's oldest prisons - and a new facility is being built.
Facility past its use-by date - union
The Corrections Association represents frontline corrections officers and its president, Alan Whitley, said the high security area, built in 1911, was past its use-by date and officers did not like working in it.
"They're working in horrible conditions up there... they're looking forward to getting into the new facility, they certainly are, they know that jail there has run its course."
People Against Prisons Aotearoa spokesperson Emilie Rākete has previously said she expected this would happen.
Yesterday, she said Corrections was still violating human rights, seven years after a huge riot at Spring Hill in northern Waikato.
"These aren't random acts of violence, these are deliberate political responses to systematic failings by the Department of Corrections.
"It happened in Spring Hill, when prisoners burned down part of one of the units in response to long hours of lockup, declining conditions and denial of basic rights guaranteed to them under the Corrections Act, and that's exactly what we're seeing here in Waikeria."
In August, the Office of the Ombudsman published a report into an unannounced inspection of the prison.
It said that while the low security areas were well maintained, the high security areas were not fit for purpose and this was seriously affecting the treatment of prisoners.
Chief Ombudsman Peter Boshier would not be interviewed for this story, but said in a statement he was monitoring the situation.
Corrections said the department was not aware of any complaints about prisoners not having access to basic items such as toilet paper.
A spokesperson said prisoners could be denied association with other inmates if their behaviour presented a risk to the security of the prison, the safety of others, or themselves.
In another statement issued last night the spokesperson said the standoff was continuing, and Corrections' focus was on ensuring it is resolved safely.
The department said they have highly trained staff with specialist skills who are continuing to negotiate with the prisoners involved.
A review into the incident has been commissioned and the reasons for the prisoners' actions will be considered.