Police are investigating after a prisoner at Auckland Prison was stabbed by another inmate.
Detective Senior Sergeant Stan Brown said the attack, which happened on Tuesday, was serious enough for the man to need hospital treatment.
Another inmate who got in the way also received minor injuries.
Mr Brown said the wounded prisoner was now back in prison but believes the pair have been segregated from each other.
Police believe there was a personal dispute between the two prisoners. No charges have been laid yet.