Parole officials in New South Wales say they will refuse parole to a convicted sex offender and self-described religious leader known as "Little Pebble".

William Kamm, 62, was sentenced to 10 years in jail in 2005 for indecent assault and having sex with a minor while in a position of authority.

Kamm was found guilty of repeatedly abusing a girl between 1998 and 2001 at his religious community near Nowra.

Kamm has served seven-and-a-half years of the sentence, and would be eligible for parole in April.

A Probation and Parole Service report stated that Kamm remains an untreated sex offender and recommended he undertake a treatment program in custody.

The NSW State Parole Authority made the decision at a private meeting yesterday, saying Kamm has so far failed to participate programs to address his behaviour.