A man who says he was sexually abused by a priest delivered two letters on Sunday addressed to Pope Francis from Chilean Catholics asking him to remove a Chilean bishop accused of protecting a notorious paedophile.

Juan Carlos Cruz delivered the letters with Peter Saunders, a prominent and outspoken British member of a papal advisory commission on sexual abuse by the clergy. Saunders on Saturday refused to step down despite a no-confidence vote, and said only the Pope could dismiss him.

The letters were left for Cardinal Sean O'Malley of Boston, the president of the commission, at a Rome guest house where the commission was meeting. O'Malley was asked to give them to the Pope, Saunders and Cruz said.

The letters involve Juan Barros, who was installed last year as bishop of Osorno. The papal appointment outraged many parishioners, national legislators and abuse victims who said Barros had protected a priest accused of having been one of the nation's most notorious sexual predators.

The priest in question has denied he abused Cruz and the bishop has denied knowledge of any wrongdoing.

"The devastation that your decision has caused us, Pope Francis, cannot withstand any more silence or omission," said one of the letters, signed by about 30 representatives of parishes in Osorno. "We have knocked on every door...and have received nothing but mockery."

Cruz, 51, sent a copy of one of the Spanish-language letters along with a statement in English to reporters. The other was a private letter to the pope from clergy in Osorno, Cruz said.

Critics in Chile say Barros was aware of and helped cover up abuse by Father Fernando Karadima, 85.

In 2011, the Vatican sentenced Karadima to "a life of prayer and penitence" for abusing children as far back as the 1950s. A judge later ruled the accusations were valid though Karadima was not prosecuted because of the statute of limitations.

Cruz says he was sexually abused by Karadima when he was 16. Karadima has denied the accusations. Barros denies he had any knowledge that abuse took place.

The letter asks the pope to "consider the consequences" of the division that the appointment of Barros has caused in the Catholic community.

In a statement accompanying the letter, Cruz said "We can never give up when it comes to protecting children and this is not the message being sent by Pope Francis appointing Bishop Barros to Osorno. This bishop witnessed my own abuse and that of many other boys over a period of 35 years."

Last year, a Vatican spokesman said the Holy See had "carefully examined the prelate's candidature and did not find objective reasons to preclude the appointment".

The Osorno controversy has taken on national implications.

During one incident at the Vatican last year which was broadcast by a Chilean television station, Francis told a group of Chileans that the accusations were cooked up by "lefties".

Last November, the country's Supreme Court formally requested that the Vatican hand over all records that the Pope relied upon to defend Barros.