Women at an Auckland prison have been routinely confined to their cells for periods of up to 29 hours at a stretch - well outside the law, which says they should get at least one hour out of their cells a day.
RNZ took evidence of the lockdown hours including a recently released prisoner's diary, to the Corrections Department, which has now launched an urgent review and pledged to stop it happening again.
But the action comes after weeks of denial from the department and its Minister Kelvin Davis that the excessive lockdown hours were happening at all.
Normally prisoners spend about 16 hours a day in their cells although Corrections has admitted that extended hours have been used to ensure physical distancing during the Covid-19 pandemic.
Any longer than 22 hours a day meets the United Nations definition of solitary confinement, and the maximum allowed under the Corrections Act is 23 hours a day.
When RNZ reported in early April that inmates were being routinely locked up for 23 or more hours a day Corrections Minister Kelvin Davis responded: "I've been advised that there is no site-wide 23-hour lockdown in place".
But now a former inmate of Auckland Region Women's Corrections Facility in Wiri, South Auckland, has shown RNZ her diary of lockdown hours.
Gil, who wanted to use a pseudonym for fear that speaking out would have repercussions for her case, was recently released from the jail which is New Zealand's largest women's prison with more than 400 inmates.
"Some days we were locked down for 29 hours and other days it would be 28 or 27," she said.
Corrections previously admitted that extended lockdown hours were being used but said that was to manage physical distancing due to Covid-19.
But Gil said the long lockdowns predated the pandemic.
"It had been already in place since January from what I understand from the other women who told me it had been going on for a few weeks before I got there."
The mother of a current inmate, who is in the unit Gil was in, independently verified the lockdown hours.
Karla, who also wanted to use a pseudonym, was worried about her 23-year-old daughter's mental health under the extreme lockdown hours in the Auckland prison.
"She's been assessed by a psychiatrist and is on a waiting list for a counsellor. She's been in there since January and hasn't seen one," Karla said. "So, no counselling; mental health issues; stuck in a cell for longer than 24 hours and then just let out for an hour - quick time for a chat, with me usually, and then back in."
Karla said because her daughter hadn't been sentenced she had no access to development programmes.
"She was really trying to get off drugs before she went in. And they said, 'No, no, no - we don't do any programs for people who are awaiting sentencing because they might just go,' and so there is nothing, absolutely nothing until you are on the other side of the wall they call it - until you are sentenced."
Corrections officers' union Corrections Association president Alan Whitley said the long lockdown hours were the result of attempts to give women a morning out of their cells one day, and an afternoon out, the following day.
"It's to alternate the time of day that they're out of the cell," he said.
"From my understanding where it's been done - it's been done at the request of the prisoners."
However, he said it probably was not within the requirements of the Corrections Act, which states prisoners must get a minimum of one hour outside their cell each day. "If you're going to hold right to that - no, it's not."
Gil's prison diary of lockdown hours shows there are four days of the week the women are locked up for longer than is allowed under the Corrections Act: Mondays - 29 hours, Wednesdays - 27 hours, Fridays - 24 hours and Saturdays - 28 hours.
'Using solitary confinement for operational reasons unacceptable'
Corrections did not deny the lockdown hours outlined in Gil's diary and a spokeswoman said that because the department "couldn't get assurances it wasn't happening" they would now conduct an urgent review.
In a statement, Corrections Regional Commissioner Lynette Cave said longer lockdown hours were a result of the prison trying to stagger the times at which women were released from their cells.
"The consequence of this is that a prisoner may be unlocked in the morning one day and then in the afternoon on the following day."
Cave said this was done "with the intention of providing fairness and equity" for prisoners and gave the example of women being able to phone children later in the day when they were home from school.
"While the intention may be good, if it means that prisoners are in their cells for an excessive length of time, it is unacceptable, " she said.
"I have asked that this practice be urgently reviewed and remedied to prevent it from occurring and seeking an assurance that all prisoners are appropriately being provided with at least the minimum entitlements set out in the Corrections Act 2004."
Amnesty International executive director Meg de Ronde said it was concerning that the prison had been using the lockdown regime for months - well before the Covid-19 outbreak.
"Routinely using solitary confinement for operational reasons is unacceptable. Solitary confinement should only be used as an absolute last resort and it shouldn't be used consistently."
Chief Ombudsman Peter Boshier told RNZ last week that Corrections had not given him adequate information about lockdown hours and discouraged him from entering prisons to check for himself.
He convinced Corrections to change its mind and is now investigating 15 prisons and detention sites, as part of his statutory role to monitor prison conditions.
The lack of transparency within Corrections went right to the top, de Ronde said.
"If we cannot rely on assurances from the minister then we should have regular routine data collection that is available for public scrutiny," she said.
"It's no longer acceptable for this to be going on with the potential for regular lockdown hours like these being used well before Covid-19."
The corrections minister had previously said prisoners who were concerned about their hours should take it up with the guards.
Documents seen by RNZ show Gil used the official complaints process but the long lockdown hours continued.
In one of the complaint forms, known as PC01s, she details being locked down for 48 hours at a stretch between 22 March and 24 March.
The response from Corrections did not deny it happened but simply says due to operational requirements sometimes prisoners may not get their minimum entitlements.
"A lot of women are putting in these complaints and trying to go through the processes but they lack the ability to be able to keep following it through," Gil said. "I believe that the staff are actually putting a lot of these PC01 complaints in the rubbish and then the girls don't bother following through with them."
Karla said that, like many in the prison system, her daughter has a history of mental health and drug problems. She said those were exacerbated by long hours in isolation and she was demanding change from Corrections.
"I'd like this to be a sustainable change for everybody who's in there to at least have time to get out of their cell and work on themselves so that when they get out they're not worse than they were when they went in."