An Auckland man who recorded a probation officer talking about supplying a paedophile with a prostitute dressed like a child says he has no doubt the incident actually happened - and likely more than once.

Corrections have launched an investigation into the allegations, saying its first step will be to establish whether the recording was legitimate.

A Corrections spokeswoman said the department would complete a review of the officer's caseload to establish if he had worked with sex offenders, and who and what the statements referred to.

It said it was yet to verify if there was a specific sex offender in question. The investigation was likely to take around two weeks.

The probation officer has been suspended while the department investigates.

On the recording the officer talks about organising a prostitute for another offender as part of a ''safety plan'' to control the offender's risk.

The West Auckland resident, who was also being managed by the man, said he recorded the meeting because he did not like some of the probation officer's comments.

He also took either his mother or father along to the meetings as a support person, because he didn't want to be alone with the officer.

"It was disgusting. He was definitely talking about a specific sex offender, saying 'I had this plan and this is what we did'."

On the recording the officer talks about the difficulty of managing people on home detention for ''pretty sick crimes'' who ''still have a need for, for instance, child sex''.

Referring to one case he says: ''I'm not able to supply them with child sex but we've worked out a plan where, hey, we'll go out to get a prostitute who comes to the house and she dresses up as a child.''

The officer says it hasn't stopped the offender's urges but stopped him having to ''grab someone off the street''.

He then says: "It's difficult talking about a chap who sits there in the lounge [and] gets sexually excited when the girls walk past going to school.

''That's what we've had to do, and because of that help they're kinda safe.''

The officer goes on to say the safety plan allows the child sex offender to integrate into the community.

''Instead of snatching someone or lurking in the bushes or progressing into something that could possibly put him into trouble he knows, he rings, happy fun times and she comes over, dresses up, does her bit and the pressure's gone. He's OK.''

There are 39 offenders in West Auckland who are managed by community probation services for sexual offences.

Corrections Department acting regional manager Alastair Riach earlier said the department did not provide or pay for the provision of prostitutes to any offenders.

''We aim to keep the public safe by working with offenders to change their behaviour associated with their risk of reoffending, and to develop a lifestyle that helps them to maintain these changes.''

- © Fairfax NZ News