Private prison company Serco has admitted it received reports of organised "fight clubs" in its prisons two months ago but will only investigate now, after fight footage was shot and shared online.
The fight clubs were a "disgrace" and showed private companies should not run prisons, the Public Service Association said.
Serco said today it would work with the Department of Corrections, the Ombudsman, and Serco staff from outside Mt Eden Corrections Facility (MECF) to investigate the fight clubs.
A report is due on August 28."I am currently at the prison, overseeing and supporting management myself," Serco director of operations Scott McNairn said today.
"...We have tough new measures in place to further enhance our regime. This is on top of the existing security activity, which has included a full lockdown search of the prison. There will be more to come."
Mr McNairn said Serco had received relevant parts of Corrections' report on allegations of organised fights in prisons.
"We noted that the allegations were not substantiated, and confirmed that recommended steps were already in place at MECF."
Corrections Association president Beven Hanlon said earlier today he'd raised concerns about the prison 18 months ago.
Two people were appointed to investigate, but the association "never heard any results", and only recently saw the report, he told Radio New Zealand this morning.
But Mr McNairn said Serco took its obligations to its staff, Corrections and taxpayers seriously.
"We do not underestimate the challenge of operating this prison. We hold 976 of the country's most difficult and challenging individuals.
"As an inner city remand prison, we manage tens of thousands of prisoner movements every year.
"Preventing violence, attempts to smuggle contraband and other criminal activity inside the prison walls is a daily reality. Our managers and staff work incredibly hard to manage these challenges."
The PSA, which said it represented 3000 Corrections staff and 100 Serco prison staff, called the prison fights "inexcusable".
"Private prisons are focussed on profit, not on ensuring safety for staff or rehabilitation for prisoners," said Erin Polaczuk, PSA national secretary.
"Private companies like Serco are not subject to the same public service ethos as those directly employed by Government."
She said staffing levels at Serco facilities were too low to ensure staff safety and proper monitoring of prisoners.
"The prison fights are inexcusable and the whole situation must be independently investigated, and the Government must commit to bringing prisons back under public control," Ms Polaczuk added.