The president of the Corrections Association says the latest attack on a prison officer, who was knocked unconscious by inmates, shows the workforce is inadequately protected.
Beven Hanlon, says the union has asked Corrections Minister Anne Tolley to allow prison officers to carry pepper spray, but the issue keeps being pushed aside.
"What we want is the same protection that policemen have. After all, the police walk around every day and they have a pepper spray and baton and stab proof vest ... just in case they come across these people.
"We deal with these people every single day in large numbers and all we've got is our cotton uniform."
A female prison officer received facial injuries while trying to seperate two inmates who were fighting at Arohata Women's Prison near Wellington on Friday.
A Department of Corrections spokesperson says the officer was trying to intervene in the fight when she was knocked to the ground. She was treated in hospital for facial injuries and discharged later that night.
The prison officer had put the inmates in an interview room when they attacked each other before turning on the officer.
Prison officers say they couldn't go to her aid as her she was lying in the path of the door.
Mr Hanlon says it's unclear whether the inmates continued to attack the officer after she was knocked out, but he said she was covered in bruises which suggested she had been punched and kicked.
The officer has spoken to the police about the incident but it is unclear whether any charges will be laid against the two inmates.