Otago Corrections Facility (OCF) general manager Dave Miller said a prisoner assaulted two staff members — hitting them in the body and head — at noon on Friday, while being moved to his cell following yard time.
"Both staff members were assessed on-site by medical staff and then taken off-site for further checks as a precaution.
"They are being fully supported by our managers and our welfare team," Mr Miller said.
A source told the Otago Daily Times the two staff members were taken to Dunedin Hospital for treatment.
Mr Miller said staff who responded secured the prisoner, who was relocated.
"The incident has been referred to police for consideration of criminal prosecution [and] the prisoner will also face internal misconduct charges," he said.
Earlier this year, a string of assaults on staff at the prison were linked to members of the hyper-violent street gang, the Crips, and last month the ODT reported that on three consecutive days staff were assaulted by prisoners in the high-security unit.
At the time, Corrections Association of New Zealand vice-president Paul Dennehy said increasingly volatile prisoners could switch from having a conversation to launching a life-threatening assault without warning.
He said OCF had gone from managing low-level prisoners to "serious, violent" offenders, often with gang affiliations.
Following the incident on Friday, additional staff and support remained in place on the unit.
"The prison has continued to carry out daily reviews of tension in all units, and this is a standard operating process for sites across the country.
"Prisons can be volatile environments, and many of the prisoners our staff work with can behave unpredictably and act without warning.
"Violence in prison is not tolerated and anyone who resorts to this behaviour will be held to account."
While prisons could never entirely eliminate the threat of violence, OCF was committed to providing the safest environment possible for staff and prisoners — investing in training and tools to keep people safe, Mr Miller said.
"This includes training in de-escalation techniques and interpersonal and tactical communication skills, through to stab-resistant vests, body worn cameras, and pepper spray."
