CANBERRA (AFP) - Disgraced Catholic Cardinal George Pell was handed a final chance to clear his name on Wednesday (Nov 13), when Australia's top court agreed to allow his appeal against child abuse convictions.

The 78-year-old former Vatican treasurer is currently serving a six-year jail sentence for molesting two 13-year-old choirboys in a Melbourne cathedral in the 1990s, but continues to deny any wrongdoing.

In a statement that took less than a minute to read and gave no hint of the deep emotions stirred by Pell's case, Justice Michelle Gordon said Australia's High Court had granted Pell "special leave to appeal".

The veteran judge said the case would "be referred to a full court of this court for argument".

No date was set for the appeal hearing, but it is not expected before 2020.

Pell is the most senior Catholic to be locked up as a swathe of child abuse cases against clergy around the world are brought.

Ms Cathy Kezelman, president of victim support group the Blue Knot Foundation, said lengthening the legal process would only cause "further potential trauma" for the surviving victim and "many others who are watching and waiting".

The father of the second victim, who died of a drug overdose in 2014, said he was "gutted" by the High Court decision.

Sydney Catholic Archbishop Anthony Fisher welcomed the decision.

"Many questions remain, and it is appropriate that these will be examined by our highest court," he said in a statement. "For the sake of all involved in this case, I hope that the appeal will be heard as soon as possible."

A spokesman for Pell said: "This matter is now still before the court and so we are unable to comment."

The case will now come before the full court of seven justices, who could decide to - in effect - reverse Wednesday's ruling, or allow the appeal to proceed. Their verdict will be final.

Pell had lost a previous attempt to overturn the convictions in Victoria state's Court of Appeal in August, but that landmark decision saw the judges split in a 2-1 verdict.

Two of the judges said the sole surviving victim, a former choirboy now in his 30s was "very compelling" in his evidence and someone who "was a witness of truth".

The third judge, however, found the victim's account "contained discrepancies" and there was a "significant possibility" Pell did not commit the offences.

Pell's legal team argued in their written submission to the High Court that the majority judges applied an "erroneous judicial method" in upholding the jury's verdict that reversed the onus of proof onto him.

Pell and his supporters have staunchly maintained he did not commit the crimes, which came to light after one of the victims went to police when the other died of a drug overdose in 2014.

Pell, who once helped elect popes, was found guilty of abusing the two boys after catching them swigging from a bottle of sacramental wine in the sacristy following Sunday mass.

During Pell's trial under a court-ordered veil of secrecy, the Vatican gradually removed him from top Church bodies with little explanation.

Pell is also facing multiple civil compensation suits, including from the father of the dead choirboy.