Cardinal George Pell has penned a letter in Australia's national newspaper just days after walking free from prison in which he says the Catholic Church has "cut out a moral cancer" by facing down child sex abuse.

The letter, published Saturday in The Weekend Australian, comes after the country's High Court on Tuesday quashed five counts against Pell of sexually abusing two 13-year-old choirboys in the 1990s, ending the most high-profile paedophilia case faced by the Catholic Church.

In the Easter message, titled: "In the suffering, we find redemption", Pell labels his initial conviction a disappointment but says he will turn the experience behind bars into spiritual energy.

"I have just spent 13 months in jail for a crime I didn't commit, one disappointment after another," he wrote.

"The sexual abuse crisis damaged thousands of victims. From many points of view the crisis is also bad for the Catholic Church, but we have painfully cut out a moral cancer and this is good."

The 78-year-old left Barwon Prison near Melbourne on Tuesday and has been staying at a seminary in the west of Sydney.

Australian Cardinal George Pell leaves a prison in Melbourne on Tuesday
Australian Cardinal George Pell leaves a prison in Melbourne on Tuesday AFP / William WEST

A jury convicted Pell in December 2018 and the decision was upheld by a three-judge panel in Victoria state's Court of Appeal last August in a split verdict.

But the High Court's seven justices unanimously found the lower court had "failed to engage with the question of whether there remained a reasonable possibility that the offending had not taken place".

After Pell's release, one of his accusers -- who cannot be named for legal reasons -- said he accepted the verdict but urged survivors of child sex abuse to keep coming forward.

"It is difficult in child sexual abuse matters to satisfy a criminal court that the offending has occurred beyond the shadow of a doubt," the man, known as Witness J, said in a statement on Wednesday.

"It is a very high standard to meet -- a heavy burden."