The appearance of the Vatican's Australian-born financial controller before a child abuse inquiry in his home country has been delayed because of illness, officials said on Friday.

Catholic Cardinal George Pell, a man once seen as a contender to become pope, was scheduled to give evidence on December 16, but his lawyer asked for permission for him to testify via videolink from Rome, citing a heart condition.

The judge chairing the Royal Commission into Institutional Responses to Child Sexual Abuse denied the request and said he wanted Pell, the Vatican's prefect of the secretariat for the economy, to testify in person.

"Cardinal Pell had previously agreed to give evidence in person," the inquiry said in a statement.

"The Cardinal's evidence relates to two case studies which involve a significant amount of complex material," it said, adding that the cardinal's video link evidence from Rome had run into technical difficulties on an earlier occasion.

The delay, until February, will frustrate victims and their advocates, who have heard testimony this year that priests suspected of abuse in Pell's former diocese were moved between parishes and put in church-appointed rehabilitation to avoid repercussions.

"I'm not disappointed, I'm furious," said David Ridsdale, a victim and nephew of a paedophile priest, who flew from London to Melbourne for the hearing, news agency AAP reported.

"I would implore Cardinal Pell to come and face the music like all of us men have had to do for all these years."

Pell, 74, has repeatedly denied knowledge of attempts to cover up wrongdoing, pointing to a non-judicial abuse compensation scheme he set up in the 1990s, one of the first for the church globally, as proof of his commitment to help victims.

In a statement, his office said Pell had booked his ticket to Melbourne, where he was to give evidence, but a cardiologist had advised him to avoid long-haul flights, as symptoms from a heart condition had worsened.

"Cardinal Pell realises there may be some who will question the decision to remain in Rome," it said, adding that Pell had consistently expressed his intention to do everything possible to assist the inquiry.

"However, it would be unwise for him not to heed medical advice."