A prison's system for assessing high-risk sex offenders and managing their sentences lacks "direction, co-ordination and governance" and requires urgent attention, inspectors have said.
Nick Hardwick, the Chief Inspector of Prisons, said too little was being done to address the risks and needs of sex offenders at Shrewsbury Prison in Shropshire, despite the fact "a significant number" were still in denial.
It was disturbing that in a prison holding so many sex offenders "systems to assess individual risk or supervise and manage sentences were so lacklustre", he added.
HMP Shrewsbury, which has been a local prison since the 19th century, became a category C training prison for vulnerable prisoners in January 2010 and held 333 inmates, most of whom were sex offenders, at the time of the inspection in September.
But despite this "there was no meaningful analysis to identify offending behaviour interventions, the range of offending behaviour work was inadequate, and too little was being done to address the needs and risks among these offenders", Mr Hardwick said.
"It was disturbing that in a prison holding many sex offenders, some presenting high risk and with a significant number in denial of their offence, systems to assess individual risk or supervise and manage sentences were so lacklustre."
The inspectors' report added that "too many prisoners, particularly those serving sentences for sexual offences, remained unchallenged in their attitude to their offence".
But Mr Hardwick said "reasonable" arrangements were in place to assess prisoner resettlement needs.
"This is a generally good report that reflects a safe and respectful institution," he said. "The regime is much improved and is more appropriate to the institution's purpose, although more needs to be done. The key role of reducing the risk of reoffending among a potentially high-risk group, however, requires urgent attention."
Michael Spurr, chief executive of the National Offender Management Service, said: "The governor and his staff are working hard to address the areas where the inspector found that improvement was required, including offender management and resettlement. Shrewsbury is already adapting quickly to its new role and preventing reoffending and protecting the public will continue to be at the core of its work."