Round the clock monitoring and housing of the country's highest-risk criminals has cost $14 million over the past five years.
Figures released by the Department of Corrections show there are now 931 emergency accommodation places for all types of inmates released from prison - a threefold increase in two years.
They include houses rented by companies contracted to do 24-hour-a-day monitoring of the highest-risk criminals.
But the department is refusing to say how much it spent over 12 years supervising a repeat child sex offender who was forced to move out of a Lower Hutt house in August.
Corrections said information on the costs of monitoring an individual would take too much research and collation to justify.
The offender was shifted after 400 residents turned out to two meetings to express concern over the decision to allow him to live in a house in Maungaraki on extended supervision.
The Maungaraki house was large - 295sq/m - and had been listed for sale this year with a suggested buyer enquiry price of over $740,000.
Corrections said it did not choose what houses offenders lived in, as that was up to whatever supervising company or trust was contracted.
As such, it said it could not provide a figure for the average weekly rental of such houses by its contractors.
It also said it did not have a budget forecast of what intensive monitoring might cost through till 2020.
The growth in the number of accommodation places for released inmates was part of an "ongoing strategy to support offenders transitioning to the community to reduce their risk of reoffending and keep the public safe," said Corrections' national commissioner, Jeremy Lightfoot.
The offender forced to leave Lower Hutt was moved to a house on the grounds of Christchurch Prison.
Corrections said it had a small number of offenders housed on various prison grounds outside the perimeter fence.