The victims of one of Australia's worst pedophiles - defrocked Catholic priest Gerald Ridsdale - want him to appear before the royal commission into child sexual abuse.

It's believed Risdale, who was sentenced to a maximum of 25 years, but could be released on parole as early as June, molested at least 40 children over three decades.

The Herald Sun says he is being urged to reveal how the church helped cover up his illegal activities before the royal commission into Institutional Responses to Child Sexual Abuse.

"If he started to talk about what he knew, the Catholic church house of cards would come tumbling down," victim Stephen Woods said.

At Ridsdale's 1994 plea hearing, witnesses told how he was moved from one parish to another when claims of abuse were raised.

He was one of the priests who preyed on children at Ballarat's St Alipius school.