Multiple investigations have been launched after a man died at Mt Eden Corrections Facility in Auckland.
Police said they were made aware of the death at about 4pm on Friday after an 'incident' at the prison.
Detective Inspector Greg Brand told RNZ the death of the man was being treated as a homicide.
"Police were made aware at about 4pm yesterday of a man who had died at the prison following an incident," he said.
"Officers continue to follow positive lines of inquiry."
Mt Eden Corrections Facility is the main prison for newly remanded prisoners in the Auckland region.
The Department of Corrections said the man's next of kin has been notified and all evidence will be given to the police.
"Corrections will also carry out a full investigation," Mt Eden Corrections Facility general manager Dion Paki said.
"As the prisoner was in a double-bunked cell, the second prisoner who was residing in the cell has been moved to a single-cell."
Paki said Corrections was expressing "sincere condolences" to everyone affected.
"We acknowledge this will be distressing for staff and other prisoners in the unit and we are providing people with support," he said.
Paki said this included access to chaplains and any cultural support.
The Inspectorate Office for the department, which operates independently, would also be investigating the death.
