Cardinal George Pell will not return to Australia to give evidence to the Royal Commission into Institutional Responses to Child Sexual Abuse despite abuse victims' calls for him to appear in person.

Commission chairman Peter McClellan​ ruled that while it would be preferable for the  Vatican-based cardinal to appear in person, he accepted medical evidence that a long-haul flight posed a serious health threat to the 74-year-old.

A hearing held in Sydney on Monday was told Cardinal Pell suffered from a number of heart troubles.

Part of a medical report from an Italian specialist was read out at the hearing.

The medical report found Cardinal Pell suffered from hypertension, ischemic heart disease, complicated by a previous myocardial infarction, and cardiac dysfunction related to the arterial hypertension.

"The undertaking of a long journey could induce an episode of heart failure and were this to occur during a flight it would also be difficult to treat," the report concluded.

Justice McClellan accepted the findings of the medical report, telling the hearing there would be a risk to Cardinal Pell's health if he flew to Australia to give evidence about alleged child sexual abuse in Diocese of Ballarat and the Archdiocese of Melbourne.

"It could not be expected that his health is likely to improve and remove those risks," he said.

"Although it would be preferable if he gave evidence in Australia, when the alternative that he give evidence by video link is available the Commissioners are satisfied that course should be adopted."

Paul O'Dwyer SC, representing two alleged victims, argued that the full contents of the medical report should be publicly scrutinised.

"One of the issues in this case is the fact that the church and particularly . . . (Cardinal) Pell, has a continuous history of non-disclosure and we would contend that this report, this medical report, is more of the same," he said.

Justice McClellan responded: "I don't share that view."

Cardinal Pell, who was a priest in Ballarat before becoming Archbishop of Melbourne and then Archbishop of Sydney before taking up a senior position at the Vatican, is scheduled to give evidence by video link from February 29 in a hearing expected to last three days.

In a separate decision, Justice McClellan ruled that the terminally ill former Bishop of Ballarat, Ronald Mulkearns, would also be required to give evidence by video link.

Bishop Mulkearns, who is suffering from bowel cancer, kidney disease and cognitive problems, was the Bishop of Ballarat between 1971 and 1997 and presided over decisions to relocate priests, including convicted paedophile priest Gerald Risdale, between parishes despite child sexual abuse allegations against them.

The commission is due to begin hearings in Ballarat on February 22 into allegations concerning Christian Brothers.