A Corrections officer is recovering after being attacked by an inmate at Christchurch Men's Prison.
The prisoner has been placed in directed segregation after assaulting the officer with a sharp piece of plastic on Friday morning.
The officer drew his pepper spray "bravely and quickly" during the attack, prison director Jo Harrex told Newshub, and the prisoner "became compliant".
"The officer has received treatment at a local medical centre and been taken home, and will be provided with ongoing support."
Harrex said other staff were quick to help their colleague and both the weapon and prisoner have been secured.
Police and Christchurch Men's Prison are both investigating the incident.
"Assaults on our staff are unacceptable and any prisoner found guilty of an assault will be held to account," Harrex said.