Canberra,  Two more Australians are set to appear on state television on Thursday to accuse Cardinal George Pell of sexually assaulting them when they were young, in fresh allegations against the Vatican's former financial chief, currently serving a six-year prison sentence for abusing two other children.

Pell, whose final appeal against his conviction is set to be heard on April 6 by Australia's High Court, was convicted in March 2019 on five sexual assault charges, committed against two choirboys of the St Patrick's Cathedral in 1996 and 1997, while he was Melbourne's Archbishop.

The new testimonies, made public on Thursday by state broadcaster ABC, were related to a dropped investigation of sexual abuse complaints against Pell dating back to the 1970's, when he was a priest in his native city of Balllarat in southern Australia

Bernie, a man identified just by his first name, grew up in an orphanage in Ballarat, and has alleged in ABC's documentary series "Revelation" - set to be aired on Thursday - that he was abused by Pell on multiple occasions.

The 53-year-old man said that he had been convinced nobody would believe him if he reported the alleged abuse, having witnessed the priest's rise to the highest echelons of the Catholic Church.

Bernie described in graphic detail how Pell - who had become a "father figure" for him - abused him.

Peter Clarke, another Australian who grew up in the same orphanage, told ABC that Pell had touched him inappropriately in the establishment's swimming pool.

Clarke said that at the time he did not understand that the priest had sexually abused him, although he recalled the pain.

The Victoria state police had recorded the statements of both men, but a planned second trial was subsequently abandoned.

Pell has maintained his innocence throughout his trial and investigations and denied all child sexual abuse charges.

Unless his appeal is successful, the disgraced priest - imprisoned since February 2019 - is set to remain in prison at least until 2022, when he will be able to apply for parole, and will remain on the register of child abusers.