George Pell has agreed to sit down for lengthy interviews in Rome for the first time since he was cleared of sex abuse charges, as part of a publicity campaign for a book put together from his prison diaries.

The Catholic Cardinal has spoken about his lowest point during the court trial into allegations he had sexually abused young boys and the “dark moments” he faced in solitary confinement.

He said the worst day was when his first appeal was rejected in August 2019.

“I was down. I was very disappointed. I came to be very cross,” Cardinal Pell said.

“(But) I said my prayers and got on with things.”

His book Prison Journal, published this month, recounts the former Vatican treasurer’s 13 months in solitary confinement following one of the most divisive trials in Australia’s history.

The 79-year-old was cleared of the charges in April.

“Look, it was bad, it wasn’t like a holiday, but I don’t want to exaggerate how difficult that was. But there were many dark moments,” Cardinal Pell said.

George Pell was convicted of sexually abusing two boys in the 1990s. The convictions were later overturned in the High Court. Photo: AAP

In a 90-minute interview with Reuters in his Rome apartment across the street from a Vatican gate, Cardinal Pell discussed the harm the worldwide sexual abuse scandal had done to the Church and the current state of affairs in the Vatican.

He again called sex abuse a “cancer” within the Church.

The Cardinal, his supporters and lawyers have suggested there could have been a link between the resistance he faced during his time as treasurer and his forced departure from Rome to face prosecution in Australia.

“I hope for the sake of the church, there’s nothing in it,” Cardinal Pell said of the theory.

“In fact— I say that quite sincerely—because some Australian people, my own family, said to me: ’Well, if the Mafia is going after you or somebody else is going after you, that’s one thing. It’s a little bit worse if it comes from within the church.

“But I think we will find out, whether there is or there isn’t [a connection].”

Cardinal George Pell talks to a reporter inside his apartment in Rome. Photo: AAP

He said the Vatican risked “going broke” unless it tames ballooning deficits and expressed hope his successor would be spared the resistance to reform that he said “thwarted” his time as the head of the Church’s finances.

He said he knew when he took the treasury job that the Holy See’s finances were “a bit of a mess.”

“I never, never thought it would be as Technicolor as it proved,” Cardinal Pell said.

“I didn’t know that there was so much criminality involved.”

Pope Francis appointed Cardinal Pell, the former archbishop of Sydney, in 2014 to head the newly-created Secretariat for the Economy and mandated him with cleaning up the Vatican’s murky finances.

The Australian ran into resistance from some Vatican officials, particularly Italian Cardinal Angelo Becciu who was then deputy secretary of state who wanted Vatican departments to continue controlling their own funds.

He left Rome two years ago to face allegations he had abused young choirboys during his time in Melbourne.

After being sentenced to six years in prison in Melbourne for crimes he insists he did not commit, Cardinal Pell was freed after the convictions were thrown out by the High Court which found there was reasonable doubt in the testimony of an accuser.

He has since returned to Rome but not to official duties.

In October, George Pell and Pope Francis allowed cameras to capture their meeting.

Meanwhile, the Holy See has been dealing with a financial scandal which is yet to result in any formal charges.

In September, Pope Francis fired Cardinal Becciu, accusing him of nepotism and embezzlement.

Cardinal Becciu had also been caught up in a scandal involving the Vatican’s purchase of a luxury property in London. He denies all wrongdoing.

Cardinal Pell, back living in his apartment has been quietly meeting with the new treasurer, Jesuit priest Juan Antonio Guerrero Alves.

“I think we are much, much better placed than we were,” Cardinal Pell said of the state of reform of Vatican finances, including new accounting and controls.

“The great challenge that lies before the Vatican is that it’s slowly going broke. Now that’s a bit of an exaggeration (but) it’s slowly happening.”

He added that he was basing his comments on public information.

Growing Vatican deficits – the 2020 shortfall is expected to be more than 50 million euros ($A82 million) – and a looming deficit of hundreds of millions of euros in the Vatican’s pension fund means potential future trouble.

“You can’t go on like that forever,” Cardinal Pell said.

“The only thing that I’m keen on is that people, in a very clear-headed way, face up to the situation.”

The COVID-19 pandemic has wreaked havoc with Vatican finances, forcing it to dip into reserves and implement tough cost controls.

Cardinal Pell said he had no doubt that Father Guerrero was honest and up to the job.

“What is important is that he continues to have the support of the Pope and that he is not thwarted the way I was thwarted,” he said.

-with AAP