Mary MacKillop, who was born to Scottish parents, worked in often harsh conditions in the Outback and will become Australia's first saint during a special Mass at the Vatican on Oct 17.
An Australian documentary due to be aired a week before her canonisation claims that she was persecuted by the Catholic Church for denouncing a priest, Father Patrick Keating, who was abusing children.
In 1871 MacKillop, then 29, was excommunicated by her bishop in South Australia for five months but it has never been clear exactly why.
The priest was disciplined but then simply moved back to his native Ireland, where he took up a job in a new parish.
The claims that she was shunned by the Church for speaking out against paedophile priests have led to calls from some Catholics for her to be made the unofficial patron saint of victims of clerical sex abuse around the world.
The Rev James Martin, an American Jesuit and an expert on Catholic saints, said the nun should be regarded after her canonisation as the patron saint of whistle-blowers.
"Now victims of sex abuse and their families and friends, and all who desire reconciliation and healing in the church, can pray to Mary MacKillop, who understands them perhaps better than any other saint," he wrote this week in "America", a respected Catholic news magazine in the US.
But sex abuse victims angrily denounced the suggestion, saying that the story of MacKillop demonstrated the Catholic Church's entrenched hostility to anyone who exposed paedophile priests.
"This priest was moved back to Ireland with no chastisement whatsoever – imagine the damage he may have done to countless more lives," said Bernie McDaid, 54, the founder of Survivor's Voice in the US, which is organising a candlelit vigil by sex abuse survivors in St Peter's Square on October 31.
"Instead it was MacKillop who was punished. It shows me that the Catholic hierarchy has been doing this for a long time, and their attitudes have not changed today. The Church is trying to move on from the sex abuse crisis, but right now it is blowing up in their face."
SIC: TC/UK