Key Points:

National Party leader John Key is "saying all the right things" when it comes to prisons but a union leader worries about the cost.

John Key said National would increase the number of prisoners in work schemes, review screening and treatment for prisoners with mental health programmes, expand literacy and arithmetic programmes and investigate the privatisation of prison management.

Corrections association president Beven Hanlon said the union would like to see more programmes in prisons but it is concerned that the only way National would be able to pay for extended programmes, tougher sentences and more prisons would be to cut the wages of prison staff.

He said the minor corruption cases in the corrections sector could increase in seriousness if pay packets were cut.

"Start paying peanuts and see what happens," Mr Hanlon said.

He said whether prisons are run publicly or privately, the tax payer still ends up paying.

"The scary thing for corrections officers around the country because the rest of the world is moving away from private prisons. Private prisons were the rage 15 years ago, they're now falling over. We would hate to see prisons the next thing that the government has to buy back - we would hate to see KiwiPrisons," Mr Hanlon said.

Mr Hanlon said the union would have liked to have seen the National party talk about the risks that corrections officers face. He said everyday corrections officers are assaulted.

The National Party is pledging to boost the number of prisoners learning industry-based skills and double those receiving intensive drug and alcohol treatment.

National Party leader John Key said today re-offending rates were too high and inmates had to learn to change their behaviour.

"At present, 43 per cent of all prisoners, and 65 per cent of those under 20, re-offend within a year of release, and we must do more to change that," Mr Key said.

"It's a waste of taxpayer money to let these people serve their time without challenging them to change their behaviour - only to release them and then throw them back into prison again when they re-offend."

Imprisonment should not just be a punishment but also give an opportunity for rehabilitation.

"Prisoners work just 15 hours per week on average, and that has to change. It's not good for anyone to have these people sitting around all day doing nothing," Mr Key said.

A National-led government would boost the number of prisoners learning industry-based skills through Corrections Inmate Employment by 1000 by 2011, at an estimated cost of $7 million.

That would increase the number of prisoners in skills-based work to 3500.

Mr Key said National was also concerned at the lack of drug and alcohol treatment beds for prisoners.

National would double the number of prisoners who are able to receive such treatment to 1000 by 2011. This was estimated to cost $3.4 million.

Mr Key said National would also allow the private sector to tender for the management of prisons on a case-by-case basis.

There was one privately run prison under the last National government, but Labour overturned this following the 1999 election,

Mr Key said National will be looking for a much better performance from the Corrections Department.

"There is also widespread public scepticism resulting from facilities such as under-floor heating and flat screen televisions now available to prisoners, especially in the new prisons," Mr Key said.

"The National Party believes prisoners should be treated humanely, but that prison facilities should be in keeping with public expectations, reflecting the fact that prisoners are paying a debt to society."

National would also:

* Ensure prisoners who are able to work but refuse are not eligible for parole;

* Carry out a stock-take of support available to released prisoners, including substance abuse treatment, accommodation and employment;

* Talk to private enterprise about opportunities for meaningful work and training for prisoners;

* Investigate whether money earned from inmate labour could be directed into victim reparations, families, or a savings fund for their release;

* Re-visit the rules around eligibility for rehabilitation programmes;

* Review screening and treatment of prisoners with mental health problems;

* Expand prison literacy programmes.