The Corrections Minister is defending the government's plan to considerably expand a Waikato prison after a protest over the weekend.
People Against Prisons Aotearoa led a protest outside Mt Eden Prison on Saturday against the 810-bed extension at Waikato's Waikeria Prison which will eventually have the capacity for 1865 beds.
The bulk of the government's $1.9 billion pre-Budget announcement would go towards construction, while nearly $8 million would go towards extending rehabilitation programmes for remand prisoners and more frontline corrections staff.
Corrections Minister Mark Mitchell told Morning Report they were investing there to deliver more prison capacity and mental health support for inmates.
The plans for Waikeria were set to go, he said.
"That's where we can deliver the capacity that we need as a government, it's also where we can concentrate and focus on a dedicated mental health unit because obviously a lot of people coming into the Corrections system have got addiction and mental health issues."
The first 600 beds would come online mid-2025, then the additional 810 beds would be available around 2030, he said.
People Against Prisons Aotearoa spokesperson Emmy Rākete said the construction of "an American-style mega-prison" was an admission of failure from the outset.
There were currently empty beds in prisons, she said.
"There's simply no case that can be made for building this - and if they do build it they will find a reason to fill it."
The government had committed to spending almost $2b on the prison at the same time as it was cutting spending in other areas, she said.
Rākete said there were some circumstances when imprisonment was necessary.
"There are definitely some people that are going to need to be securely maintained, but that doesn't mean we should have 10,000 people in prison as we will soon under this government's direction."
Rākete said the group was dedicated to fighting against the mega prison because it was committing huge amounts of money to something which would not work.
"You can't give people mental health treatment while keeping them in a enormous concrete cage, miles away from their families, in the middle of rural Waikato.
"So we're going to fight it because the only alternative would mean consigning future generations to suffering just as we have done in this country over generations now."