The Government is widening the investigation into organised fights in the prison system and says it's putting the company that runs Mt Eden prison on notice.
A video published on social media showed an organised fight between inmates at the prison, filmed by smuggled smartphones.
Warning: the video below contains graphic images, which may be disturbing to some viewers.
The investigation will be done in two parts. The first phase will look at the brawl itself and whether a fight club was operating at the prison.
It will be completed by the end of August.
The second phase will seek to establish if the controls designed to stop prison violence were good enough and will also investigate how inmates were accessing cellphones.
Corrections Minister, Sam Lotu-Iiga, said the behaviour was unacceptable, and the review would find out how it was able to take place.
He said the company that runs Mt Eden prison, Serco, was on notice and he is meeting with its management this week to discuss the footage.
Serco is carrying out its own internal review.
The prison officers union said an inmate who refused to take part in one of the fights was thrown off a prison balcony and broke both of his legs.