Hundreds of sex offenders are being placed in shared prison cells despite warnings that it is dangerous and should be stopped.
Figures from Corrections show that in October this year there were 674 double bunked inmates who had a previous or current sex offence.
An advocate for sex abuse survivors, Ken Clearwater, said sharing a cell with a sex offender could be terrifying for inmates who had been raped in the past.
"If you're in with somebody who has got power and control over you, if that person is a bit bigger, or may be a gang member or something like that, and you have to do what you're told to.
"Unfortunately, in our prison system it's very hard for you to speak out if something does happen to you."
The number of double bunked sex offenders fell by 104 between June and October but Mr Clearwater, chair of the Males Survivors of Sexual Abuse, said that was still too high.
"To have sex offenders going into double bunking with another male is absolutely inhuman and I just can't believe that they still do it."
Despite the recent dip, double bunking has largely risen over the past four years.
Corrections chief custodial officer Neal Beales said the department could not block sex offenders from being roomed with other inmates.
"All you've got to do is look at the prison stats at the moment and see how many people we've actually got in prison with a sex offence.
"We have a lot of people in prison who are sex offenders who do not present a risk to other prisoners and have not presented a risk to other prisoners."
Mr Beales said prisons ensured no high risk sex offenders were double bunked by using a risk assessment tool for evaluation. Those deemed non-threatening under that assessment could share.
"Somebody may be a predator, but only target, for arguments sake, young females," Mr Beales said.
"You know if you put them in a cell with an adult male who is older than them or the same age, he is no threat to them."
A review was sparked last year after William Katipa - who was in jail for raping a young mother and teenage girl - was convicted for raping three cellmates.
It found though the assessment criteria for identifying risky prisoners were sound, the process was under pressure because of overcrowding.
"I'd prefer that there was no double bunking in New Zealand's prisons at all, but it is a situation we inherited … that doesn't necessarily mean that they pose a threat."
In an interview with RNZ earlier this year, Corrections Minister Kelvin Davis said sex offenders would have their own cells in the new Waikeria Prison, due to open in 2022.
Now he could not guarantee that.
"Their prior convictions are considered during the assessment and there are a multitude of factors that are relevant, and a sexual conviction doesn't preclude a prisoner from being double bunked."
Mr Davis said he hoped a reduction in the prison population would bring an end to double bunking.
