Some sex-offender prisoners who want treatment in prison cannot access it, Mr Sean Aylward, the director-general of the Prison Service, has acknowledged. "We are not reaching everyone who is interested at the moment," he said.
"There are people coming forward who we're not reaching. There are others not coming forward because they would have to move prison to get treatment, away from their families."
However, he said, the sex-offender treatment programme was being expanded, and it was hoped that within a year it would reach all prisoners seeking it.
At the moment there were no incentives for prisoners to seek treatment, and the demand would be likely to rise steeply if incentives, such as reductions in sentence for those participating in treatment programmes, were to be introduced.
Mr Aylward said the issue of incentives was a difficult one, but added: "We want to have a treatment ethos in the prison, an expectation that prisoners would undertake this work."
He said that in some countries, such as Scotland, sex offenders were not considered for parole programmes unless they had participated in a treatment programme. "There could also be provision of post-custodial supervision," he said.
"These are policy issues. The interest of the Prison Service is in reducing recidivism and promoting community safety."
He said he had commissioned a report on sex-offender treatment from Dr Francesca Lundsgrm. This would include a critique of the counselling programme already in use, an examination of best international practice and of independent accreditation procedures, and a manual for delivery of the programme.
Mr Aylward said the programme would be multidisciplinary, involving prison officers, probation officers, teachers and psychologists.
"The psychology service and the probation service will continue to provide guidance and the overall framework," he said. Already a "thinking skills" programme, involving training in anger management, was going well in three prisons, he said. This was delivered by specially trained prison officers.