ACT leader David Seymour says the prison population will rise if his party is elected to power in October.
Appearing on AM on Thursday, Seymour said New Zealand had "descended into lawlessness" and locking people up was the unfortunate answer.
"I'd just make the point that, if it keeps the streets safe, it may be the best money you ever spend."
ACT is promising to roll back Labour's 2017 plan to reduce prison numbers by 30 percent over 15 years. Part of that involved spending $1 billion on building another 500 prison beds to "ensure there is sufficient capacity for dangerous people to be locked away from law-abiding New Zealanders".
Seymour said funding for such a plan was possible under ACT's alternative Budget.
He noted ACT was also "entirely in favour of rehabilitation".
"I just think we should lock them up first. Under this Government, they're not locking them up and they're not rehabilitating them when they do, and people are tired of feeling so unsafe."
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