A man was seriously injured following an alleged attack at Paremoremo Prison yesterday afternoon.
Emergency services were called to the Auckland prison just after 3pm yesterday after a male, aged in his 20's, had been stabbed.
Prison Director Andy Langley confirmed a prisoner was taken to hospital after an alleged assault.
"The area in which the assault took place is secured as a crime scene and police have been informed," he said.
"Corrections will also carry out a full investigation into the incident, and will ensure all evidence is provided to police."
Langley said they have a zero tolerance for violence policy.
"Any violence or assaults against other prisoners or staff is not tolerated in prisons.
"Any prisoner using such behaviour will be held to account for their actions, including facing criminal charges."
He said staff are constantly working to ensure the prison provides the safest environment possible for staff and prisoners.
"Our staff manage some of New Zealand's most dangerous people in a complex and challenging environment.
"Over 75 per cent of the prison population have convictions for violence in their offending histories, and more than 90 per cent have had a lifetime diagnosis of a mental health or substance abuse disorder," he said.
A spokesperson said the victim was not the man charged over last month's massacre in Christchurch.