Three investigations are under way into "potential excessive use of force" by guards responding to the stabbing of an officer at the maximum security Auckland Prison at Paremoremo.
Two officers were suspended after the incident on May 20, which is believed to be part of a series of tit-for-tat events involving Killer Beez gang founder Josh Masters.
According to a well-placed source, the sequence began in late April when Masters and another prisoner allegedly punched a female prison guard in the face.
Prison officers responded by "throwing punches of their own", said the source. One allegedly punched Masters, who is serving a 10-year sentence for drug-related offending, and pushed him to the ground.
Masters, a former kickboxing champion and aspiring rapper was moved to the isolation unit where it's believed he remains.
The source said that on May 19, prison management received an anonymous email threatening the safety of the officer who allegedly punched Masters.
The next day the officer was stabbed. He was wearing a stab-resistant vest at the time of the attack but spent the night in hospital with, the source said, "multiple stab wounds to his head and neck".
The source alleged the officer who was stabbed and two others set upon three prisoners, believed to be linked to Masters. They were taken to hospital after the attack, it is claimed.
"One of the inmates' heads was so swollen it looked like a pumpkin, you couldn't see his eyes and he was purple," said the source. "Another inmate involved in the brawl had his foot stomped on so badly it bent back the other way."
Prison director Andy Langley said he had looked into the incident personally.
"I reviewed the CTV footage and was concerned about the potential excessive use of force. I immediately referred the issue to police in its entirety.
"Changes to the management of the wing where the incident took place were also made immediately."
Corrections is carrying out a full operational review and the Office of the Inspectorate - a team of independent inspectors - is doing its own investigation into the incident and any connected events.
"This will include the inspector meeting with all involved prisoners and their family members and partners," said Langley. "Inspectors report on the fair, safe, secure and humane treatment of prisoners and people detained within the Corrections system. The investigation will be completed at the end of the month."