Shipping container prisons only if humane - Key

Prisons will only be built out of shipping containers if they are safe and humane, Prime Minister John Key says.

Corrections Minister Judith Collins was floating the idea of prisoners building their own cells from shipping containers.

Opponents say the proposal is inhumane.

Mr Key said there were not enough beds for the growing number of prisoners and prisons built by the previous government were too expensive.

"The (Corrections) Minister, rightfully so, is just saying `look there are other options out there, let's explore all those'," he told TV1's Breakfast.

"I wouldn't say we are going to do this. It's just that I don't know at this point. We're assessing all of the options available to us."

The prefabricated shipping containers were used overseas but would not be introduced here if they were not humane, sensible or secure, Mr Key said.

However, prisons did not need to be luxurious, he said.

The prison population is continuing to swell, with 700 added to the muster this year, and tougher sentencing is worsening the problem. Measures such as double-bunking are being implemented.

Ms Collins has asked the Corrections Department to consider the proposal, which she described as "a great idea" and "a lot better than being locked up all day in a cell".

The container cells would "be spartan but humane and clean" and prisoners could help build them.

Rethinking Crime and Punishment director Kim Workman said the idea of putting prisoners in containers was inhumane.

The cost of building accommodation to the standard of the new Spring Hill prison in Meremere, south of Auckland, works out at about $643,000 per bed. Using shipping containers, the cost is an estimated $380,000 per bed.

- NZPA