Inmates there had fewer barriers than other prisons because of their security classifications which is why some were allowed in work schemes.
"If a minimum-security prisoner breaches the trust they have earned through good behaviour, their security classification is increased. This usually results in them being transferred to another prison site with higher security," Mr Buffery said.
News of the embarrassing escape quickly spread, with details appearing on websites around the world.
Police say Hughes should not be approached. Anyone who sees him should call 111.
He is a Maori, 1.60m tall and of thin build. The vehicle he is believed to have taken is a white 2005 Toyota Landcruiser, registration CPU985, with a large grey speaker attached to the roof.
Private prison operator Serco has been fined $150,000 after a prisoner dubbed "Houdini" escaped from the new Mt Eden Corrections Facility.
Aaron Stephen Forden fled the prison complex last October, having famously escaped from the old Mt Eden Prison in 2008.
He was recaptured a week later and is being dealt with by the courts.
Corrections Department chief executive Ray Smith said he had determined it was appropriate to levy a financial penalty for this escape under the terms of the contract with Serco.
A Serco spokesman said Corrections was "entitled to levy that as a fine" and its main focus was on ensuring the safety of the public, staff, and prisoners. The department said security at the complex had been reviewed and improved since the escape.