Violent crime surge puts pressure on prisons

A steady increase in violent crime and offenders spending longer in jail have combined to put the prison service under pressure, the Corrections Department says.

In its briefing to new Corrections Minister Phil Goff, the department says the number in its 20 prisons has grown 40 per cent in seven years, reaching a peak of 8457 on September 10.

The muster currently stands at 8200 and, on any given day, the department also manages 30,000 community sentences and orders.

"Ongoing growth in the prisoner population ... places facilities, operations and staff under considerable pressure," it told Mr Goff.

An assessment of its prison capacity had found more than half was below acceptable standard and needed to be replaced, decommissioned or refurbished.

"A plan to complete such work by 2014-15 has been drafted."

It had also identified obsolete facilities that were unsuitable, below standard and uneconomic because they would cost more to bring up to standard than to replace.

Among key challenges were a high ratio of inexperienced to experienced staff, continued staff shortages in some areas, and the need to build public confidence in the department.

"Annual prisoner forecasts for each of the last few years have all indicated continued growth into the future at a rate above that of the general population," it said.

Total crime had been relatively stable but violent crime had increased steadily for the last 20 years.

"The number of convictions, and the number of sentences of imprisonment, has continued to rise. Average sentence lengths have not changed significantly but prisoners tend to serve a greater proportion of the sentence in prison, with release on parole tending to be delayed."

Numbers on remand, and their length of time in custody, had also risen.

The average cost of keeping an offender in prison is $76,639 a year.

Escapes had fallen 83 per cent over the last decade and drug use had fallen from 34 per cent in 1998 to 12.7 per cent now.

Maori were over-represented at every stage of the criminal justice process, making up 50 per cent of those in jail and 42 per cent of those on community service.

They comprise about 15 per cent of the general population.