Muslim sex offenders could be allowed to opt out of a treatment programme being run by the Prison Service because it is against their religion.

The service's Muslim adviser, Ahtsham Ali, said there is a “legitimate Islamic position” that criminals should not discuss their crimes with others, as required in the Sex Offender Treatment Programme.

Although Mr Ali has not yet called for changes to the rules, he told prisoners’ newspaper Inside Time: “I will be taking it forward as a matter of some urgency with colleagues, including those with policy responsibility for the Sex Offender Treatment programme, who I know are very willing to consider and discuss these issues.”

The possibility of an exemption for Muslims came to light after an unnamed prisoner wrote to the newspaper asking to clarify the position of Muslims on the programme.

"I have always insisted that it was against Islamic teachings to discuss your offence to anyone, let alone act it out within a peer group,” the prisoner wrote.

Mr Ali responded that the issue had been raised twice before, but there had not yet been a review of the rules relating to the treatment programme.

A Prison Service spokeswoman said that the next set of rules for the Sex Offender Treatment Programme would be sensitive to the needs of different faiths. “We are currently seeking to ensure that the policy for the Sex Offender Treatment Programme is sensitive to the diversity of religions within the prison context," she said.

“The programme is suitable for any prisoner with a current or previous conviction for a sexual offence, or another offence which has an identifiable sexual element.

“Membership of a particular religion is not a bar to participation in accredited programme."

Experts said today that being excused from treatment programmes should mean spending longer locked up.

Mark Leech, editor of the Prisons Handbook, the 850-page annual guide to prisons in England and Wales, said: “Muslims who don’t want to take part in the course may have to spend more time in prison, because their risk of reoffending will not be assessed as part of the treatment programme," he said. “This would be quite right, because we have to think about the victim.

Harry Fletcher, assistant general secretary of the National Association of Probation Officers, said: “The logic is that Muslims cannot take part in offender programmes and therefore their offending behaviour cannot be assessed and they are unlikely to be granted parole.

“They may then seek legal redress through judicial review on the grounds that they are being discriminated against on the grounds of religion.

“If they do not take part, Muslim sex offenders are likely to serve longer sentences, possibly the whole of their term, before they are released.”

The Conservatives backed their calls. Nick Herbert, Shadow Justice Secretary, said: “It is one thing to make a dispensation for a prisoner’s faith when it comes to prayer and diet, but if a prisoner is unwilling to take part in rehabilitation, they should be treated no differently to others - which may mean spending longer in custody."

Times Recommends

• Sarah Brown and the ladies who tweet
• Open letter to a hero's daughters, from the daughter of a murdered officer
• Transplant drug extends life in mice