A convicted child sex offender believed to be paying children to work for him is possibly grooming them for sex, says a child sex expert.
Corrections Department principal psychologist Bronwyn Rutherford, who manages Christchurch Prison's Kia Marama sex offenders programme, said any former sex offender associating with children without supervision wasa danger.
"What we know about any sort of behavioural problem is that the best predictor of their future behaviour is their past behaviour," she said.
It was revealed last week that the Hamilton man convicted of sexually abusing his son and daughter was paying children to work around a tree house.
The man had taken photographs of the children.
The man admitted he paid a 15-year-old living in his neighbourhood to help him strip his house and that the boy's younger brother and sister also went to his house.
Ms Rutherford said by having a tree house on his property the man, who has name suppression following the convictions, was increasing his chances of reoffending.
"If someone lives on their own and they put things on their property that are attractive to children they will draw them to their property and that's a real risk," she said.
Ms Rutherford said child sex offenders who agreed to undergo either Christchurch's Kia Marama programme or Auckland's Te Piriti programme were told on release to never again associate with children unsupervised.
The Corrections Department can't make anyone undergo the treatment. It is not known if the man living in west Hamilton has been on the programme.
"When anyone leaves the treatment they are made to work on a safety plan to stop them reoffending and a standard part of that plan is for them not to be in the presence of children without the presence of an adult," she said.
Ms Rutherford said any unsupervised interaction could cause child sex offenders to reoffend.
The parents of the children being paid to work for the man refused to comment.
Children's Commissioner Dr Cindy Kiro said the man was a clear risk to the children. "There's no question in my mind that people convicted of child sex abuse...and someone convicted so recently as November 2000...require close supervision.
"The fact he's got these children doing odd-jobs around his house should raise questions in his own mind...he should recognise there is a real risk for him to reoffend."
