The safety of prison staff and inmates must be ensured and the minister responsible should step up or stand down, NZ First says.
The party's corrections spokesman, former senior prison officer Mahesh Bindra, says the latest attack in Auckland's maximum security prison at Paremoremo shows there's a problem.
The prisoner, in his 30s, was seriously injured in yesterday's attack and was taken to hospital.
"Every time a violent incident takes place there is this rehearsed line 'violence will not be tolerated' but clearly nothing is done because it keeps happening," Mr Bindra said today.
"The Government spends over $100,000 of taxpayer money per prisoner, per year, in maximum security environments and New Zealanders need to know it's put to good use."
Mr Bindra says the buck stops with Corrections Minister Sam Lotu-Iiga.