The Department of Corrections is limiting prisoners' access to fruit, saying a prison riot earlier this year was a result of inmates fighting after getting drunk on homebrew made from fruit and hand sanitiser.
Twenty-three inmates are facing charges following the riot at Waikato's Spring Hill Prison in June, which lasted for 10 hours and caused more than $1 million in damage.
The department's chief executive, Ray Smith, told Parliament's Law and Order select committee on Wednesday that the riot was caused by fighting among gang-affiliated prisoners who were drunk on homebrew made from fruit and an alcohol-based hand sanitiser.
As a result, inmates will now get two pieces of fruit a day and will only be able to buy an extra seven pieces a week to prevent stockpiling.
The hand sanitiser is being replaced with a non-alcoholic variety.
Mr Smith said there are also new rules so serious assaults on Corrections staff will result in prisoners going into maximum security within 48 hours.
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