The Corrections Department says it's relatively uncommon for prisoners to escape from work parties.
A low security inmate, Arai Whakaari Hema, 30, escaped from Auckland Prison at Paremoremo on Wednesday. He was part of a painting crew doing maintenance outside the wire.
Police say Hema should not be approached.
It's the third escape by prisoners in the North Island in the past week: three who escaped from a prison van in Hamilton are still at large.
On 15 January, two prisoners broke out of a police van at Palmerston North District Court.
National operations manager Robin Benefield says Hema was part of a painting crew doing maintenance outside the wire.
He told Summer Report such an escape is rare and the incident is being investigated.