A document purportedly voicing grievances of Waikeria prisoners claims inmates have filthy drinking water and must eat from paper bags next to open, shared toilets.
Some claims outlined in a "manifesto" circulating online have been relayed to MP for Waiariki and Māori Party Co-Leader Rawiri Waititi, who was racing to the jail before sunset on New Year's Eve.
It comes as one of the 17 inmates surrendered this afternoon and is now speaking with police after being assessed and cleared by medical staff.
Negotiations with the remaining 16 prisoners are ongoing and a Corrections spokesperson said they are being encouraged to comply with instructions from staff.
The document alleges drinking water in the Waikato prison is brown, inmates have had to use towels for three straight weeks, and some have not had bedding changed in five months.
Prison abolitionist group People Against Prisons Aotearoa uploaded the manifesto on New Year's Eve.
"We have no toilet seats: we eat our kai out of paper bags right next to our open, shared toilets," the author or authors of the document added.
"We have not received clean uniforms to wear for three months. We wear the same dirty clothes day in and day out."
"We have to wash our clothes in our dirty shower water and dry them on the concrete floor."
A spokesman for Waititi said the MP had heard almost all of the same complaints as were circulating in the manifesto.
And a woman who'd been in daily phone contact with her protesting partner inside the jail told the Herald: "He gets fed out of a paper bag - not on a plate - and has to eat it in his cell where he goes to the toilet."
The Department of Corrections was approached for comment about the latest allegations circulating online.
One-third of Waikeria's bed capacity has been destroyed since unrest erupted on Tuesday.
Prisoners lit fires in an exercise yard before climbing onto a roof.
Corrections chief executive Jeremy Lightfoot earlier said it was not known why the prisoners started rioting, but the reason could be an alleged lack of access to phones.
He said after fires were lit in an exercise yard, the whole jail was locked down.
Lightfoot said a maximum of 21 inmates were non-compliant and destructive but four of those surrendered by Wednesday.
A Corrections spokesperson said one inmate involved in the disorder surrendered this afternoon and was removed from the top jail.
The spokesperson said police were responsible for determining whether charges would be laid against anyone in relation to the incident.
Meanwhile, Waititi was taking a 360km journey from Cape Runaway to the Waikato prison on New Year's Eve.
"He's got a tight timeframe. They've given him till sundown," a spokesman for Waititi told the Herald at about 7.30pm on New Year's Eve.
He understood prison management told Waititi he'd have to arrive by sunset if he wanted to talk with the protesting prisoners.
Waititi earlier on New Year's Eve said the 17 prisoners had taken over part of the jail in protest at inhumane treatment.
"I have been contacted directly by a number of prisoners who have made it very clear that they are unwilling to meet with anyone but myself to discuss their concerns" Waititi said.
"I've heard their call and I am making my way to Waikeria to meet with them, to listen, to support their call for justice and work towards a solution."
"These men belong to whānau. They are fathers, brothers, sons and uncles."
He said the inmates deserved the right to humane treatment, fresh water, food and clean clothing.
The union for prison staff earlier this week said guards worked in "horrible" conditions where the rioting was happening.
Corrections Association president Alan Whitley said part of the prison was well past its use-by date.
In April 2019, a spate of assaults was reported at the prison. The violence included attacks on guards by inmates, and prisoners fighting among themselves.