Prison beds bill set to top $1.75b

The prison population is growing exponentially and will require 4900 new beds at a cost of $1.75 billion in the coming seven years, Budget documents reveal.

The prisons are virtually full now, but the Treasury's Budget documents show that Corrections forecasts the present population of 8000 to grow to 11,000 by 2016. The documents say the bulk of the $1.7 billion will hit next year's Budget.

Growth in the prison population will require the construction of 3500 new beds and the replacement of 1400 - a total of 4900 beds.

The documents show that as well as the prison being considered for Wiri, there is building at another two sites planned - although details are deleted. The Budget included $385.4 million for double bunking at existed prisons, with Corrections Minister Judith Collins saying without it prisons will be full by February.

The Government is looking at other alternatives, such as adding on converted shipping containers or prefabricated "concrete pods" to existing prisons.