Acting prison director of Rimutaka Prison Steve Morgan said public safety was the top priority and a full operational review into the circumstances of the incident was under way.
"We expect this review to identify how this incident occurred and what action can be taken to prevent this happening again," Morgan said.
"As this is subject to police investigation we are limited in what further detail we can provide, but can confirm the prisoner was accompanied by two custodial staff and handcuffed."