Corrections Minister Anne Tolley says a prison guard, or the union that represents guards, put the public at risk by leaking information about a prisoner being transported on a commercial flight.
A picture of the prisoner appeared on the front page of The Dominion Post on Friday. The minister's office says it understands the information came from either a Corrections employee or the Corrections Association.
Association president Beven Hanlon agrees the leak is concerning, but denies union members are to blame.
Mr Hanlon says Ms Tolley is trying to divert attention from serious safety concerns about transporting high-risk prisoners on commercial flights.
