Corrections Minister Kelvin Davis has issued an embarrassing clarification after saying he didn't see the latest prison population projections before deciding to build a smaller prison at Waikeria.
The newly released Ministry of Justice report, from 2017, has the prison population increasing by an additional 2000 people compared to the previous forecast.
It's now forecast to increase by more than 4000 by 2027 - that would take the prison population from 10,300 in June 2017 to 14,400 in June 2027.
The projections were completed in October, the report says, with the figures not released publicly until last week.
On Monday morning Mr Davis said he hadn't read the report until Sunday night.
The admission that he hadn't read a months-old report before making a crucial decision on the size of Waikeria Prison was met with surprise, leading the news at the next hour.
Mr Davis said the Government would treat the projections as a "warning", not a "target." He said there's been a 300-person decrease in the prison population since January.
Several hours later, Ms Davis' office issued a statement saying the Waikeria rebuild decision was actually based on the 2017 projections.
"My comments this morning were intended to convey that I simply had not read the public version of the report on the projections, which was published last week. Of course I've seen dozens of official reports based on the information in the projections," Mr Davis said.
The Government decided to build a 500-bed prison and a 100-bed mental health unit to replace the run-down high-security block at Waikeria Prison. The previous Government had planned 1500 beds, a prison labelled "American-style" and a "mega-prison" by the current Government.
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Opposition leader Simon Bridges said the decision to build 1000 fewer beds at Waikeria was "downright reckless".
"He can either do the right thing and build the required number of prison beds while also coming up with a real plan to reduce crime, or he can make it easier for criminals to get out of prison and harder for them to get there in the first place."
The Government is planning an overhaul of the justice system as part of a goal to reduce the prison population by 30 percent. That could mean changes to bail and parole, after a law change saw the prison population increase beyond projections.
More than half - 2400 - of the projected increase is down to the "ongoing increase in the custodial population in the next 10 years", according to the report. An additional 1700-person increase is in the sentenced population, "driven by an expected increase in the number of more serious cases passing through the system as well as people being released on parole at a later point".
The length of time on remand has "been rapidly increasing" from 60.1 days in 2014 to 71.5 days, the report states.
The report does not reflect the impact of any future legislative or procedural changes.