A "wickedly manipulative" serial paedophile priest has had his jail sentence extended until at least 2026 for the sexual abuse of boys at St Stanislaus College in Bathurst in the state's central west.

Brian Spillane, 74, was found guilty last year of sexually abusing seven students between 1974 and 1990, in what a Sydney court heard was likely to be the last in a series of child abuse cases against him relating to more than 30 children.

District Court judge Robyn Tupman today sentenced him to at least nine years in jail and a maximum of 13 years for 16 offences including buggery against boys as young as 12.

Judge Tupman said Spillane abused his position of trust as a teacher and chaplain and "used religious rituals to increase his power over his victims".

"Most of the complainants were boarders a long way from home and in many cases away from home for the first time," she said.

"Many of the complainants didn't realise what was happening was inappropriate, in large part because he was a priest.

"They didn't tell anyone for many years. Perhaps more insidiously, they didn't expect to be believed.

"He knew that he could act with impunity and there was almost no chance his offending would be revealed."

Spillane worked as a chaplain at Bathurst's St Stanislaus College. ( ABC News )

The judge described Spillane as "wickedly manipulative", saying the former priest drugged one victim and raised the serious illness of the mother of another to convince him not to tell his family because he said it would make life harder for her.

Spillane was already serving at least 11 years for the abuse of boys and girls both at St Stanislaus College and during his work as a priest in Sydney and regional New South Wales.

He will be eligible for parole in November 2026.