Corrections has paid about $2 million over 18 months on hotel rooms for extra guards at Mt Eden prison.
Corrections needed extra guards when it took over the management of Mt Eden Corrections Facility (MECF) last year.
Video footage of "fight clubs" within the Serco-run prison were posted online in July 2015, sparking an investigation by Corrections' chief inspector and eventually leading to the decision to end Serco's contract.
Corrections northern regional manager Jeanette Burns said the department had been rotating staff from around the country to Mt Eden for the past 18 months to improve safety.
Some were in Auckland, but others needed to be put up in accommodation, including the four-and-a-half star Adina Hotel.