The Australian cardinal suggests there is evidence - but not proof - that his prosecution was related to his work.

"There's smoke but we don't have proof of fire," he said during the virtual launch of his book, Prison Journal, from Rome on Wednesday.

"But I come from a bushfire country and sometimes the entire state is covered with smoke."

Pell ran into stiff resistance from the Vatican's old guard during the three years he tried to impose international financial transparency, budgeting and accounting standards on the Holy See bureaucracy.

He on Wednesday repeated unsubstantiated and unsourced Italian media reports suggesting money was sent from the Vatican to Australia to influence his prosecution.

There is no indication an active investigation is under way in Australia or the Vatican.

"I myself am quite confident that money did go from Rome to Australia about that time but I've got no proof about where that finished up," Pell said.

He said he had no intention of seeking damages from the Australian government for his incarceration.

Pope Francis' former treasurer left his job as prefect of the Vatican's economy ministry in 2017 to face charges he sexually molested two 13-year-old choir boys in the sacristy of the Melbourne cathedral in 1996.

After a first jury deadlocked, a second unanimously convicted him and he was sentenced to six years' jail.

The conviction was upheld on appeal only to be thrown out by Australia's High Court, which in April unanimously found reasonable doubt in the testimony of his lone accuser.

Pell said he now intends splitting his time between Sydney and the Vatican, where he he has met with many old collaborators and friends since returning, including emeritus Pope Benedict XVI.

Pell told journalists he believed Benedict should be made a doctor of the church one day - the church's highest honour that is bestowed after someone is made a saint.

But he said going forward, the Vatican must quickly adopt regulations governing resignations of future popes.

It was a reference to the unprecedented situation of having two popes living in the Vatican, with Benedict still a point of reference for traditionalists nostalgic for his doctrinaire papacy, some of whom have refused to recognise Francis as pope.

"Obviously we love the popes, we have great respect for them," Pell said.

"But the needs of the situation - the unity of the church - is on another level that goes beyond a personality."

During Wednesday's presentation, Pell also praised US President Donald Trump's "splendid" Supreme Court appointments and defence of Christian values.

However he questioned his effort to sow doubt in the integrity of the US presidential election.

"It's no small thing to weaken trust in great public institutions," he said.

At one point in the book, Pell says Trump is unfortunately "a bit of a barbarian but in some important ways, he is 'our' barbarian".

During the virtual press conference, he said Christians had an obligation to bring their values to the public and Trump had made a "positive contribution" particularly with his three Supreme Court picks, two of whom are Catholic.

"In other areas, I'm not sure that he's been sufficiently respectful of the political process."

Australian Associated Press