Central to the course, which is Christian and multidenominational, is a mysterious three-day spiritual weekend, known as the Cursillo, or journey, which helps prisoners to reappraise their values. The Kairos principles were first established in Brazil in 1972 and have been taken up by over 150 medium- security prisons in America.
In the Verne prison, in Dorset, the project has brought a new calm to D Wing, which was once so violent inmates referred to it as "Beirut".
But, according to a confidential Prison Service report on Kairos-APAC written last month, the claims of organisers that the project dramatically reduces reoffending rates are open to question.
The author, the prisons expert Ursula Smartt, warns: "Currently, results are only superficial and it is not clear whether prisoners on the Kairos scheme are only `behaving' in order to `beguile' the Parole Board." Ms Smartt observes that probation officers have been reporting that increasing numbers of prisoners are turning to religion while serving their sentences.
She quotes prisoners who have chosen not to go on the Kairos project expressing doubts about the sincerity of some of those who have.
One 26-year-old inmate from Wales said: "Half of them who go on there haven't got a religious bone in their body; I'm sure that some of them turn religious for the time they're inside and when they're out they'll just revert to their own criminal self."
Ms Smartt notes: "It is important that prisoners on the Kairos scheme do not regard this as an easy `cop-out'."
But the Prison Service said Kairos had already reduced drug use and violence at the Verne. A spokesman said inmates of the project were subjected to "a challenging experience" and were under pressure from their peers to improve their behaviour.