The Corrections union is sounding the alarm on prison capacity.
The Ministry of Justice projects the prison population will increase 36 percent by 2035 to more than 14,000 people.
The Corrections Association of New Zealand says facilities are already at 95 percent capacity.
National President Floyd du Plessis says he predicts it will be completely full within 18 months.
He says some projects will slightly help - but more serious action needs to be taken now.
LISTEN ABOVE

Gavin Grey: UK correspondent on Labour's poor showing at the local elections
03:41

Geoff Bertram: energy economist on the Greens calling for the Government to bring down power prices
05:43

Shane Solly: Harbour Asset Management expert on the market reactions to the 'no deal' announcement on the Middle East conflict
03:07