Cardinal George Pell, whose conviction on child abuse charges shocked the Catholic Church before being quashed, has died at 81.

The former Vatican treasurer is Australia's highest-ranking Catholic cleric, and the most senior Church figure ever jailed for such offences.

He died of heart complications after hip surgery, Church officials say.

Cardinal Pell served as Archbishop of both Melbourne and Sydney before becoming one of the Pope's top aides.

He was summoned to Rome in 2014 to clean up the Vatican's finances and was often described as the Church's third-ranked official.

But the cleric left his post in 2017, returning to Australia to face trial on child sex abuse charges.

A jury in 2018 found he had abused two boys while Archbishop of Melbourne in the 1990s.

Cardinal Pell, who always maintained his innocence, spent 13 months in prison before the High Court of Australia quashed the verdict in 2020.

However a civil lawsuit - launched by the father of a choirboy who prosecutors alleged Cardinal Pell abused - is still underway.

Meanwhile, a landmark inquiry found that he knew of child sexual abuse by priests in Australia as early as the 1970s but failed to take action.

The Child Abuse Royal Commission ran for several years, interviewing thousands of people, and its findings relating to Cardinal Pell were released after his acquittal. Cardinal Pell denied the allegation, insisting it was "not supported by evidence".

Archbishop of Melbourne Peter Comensoli paid tribute to Cardinal Pell as "a very significant and influential Church leader" while Australian Prime Minister Anthony Albanese said his death would be a "shock to many".

Former Prime Minister Tony Abbott - a Catholic - praised the cleric as a "saint for our times" and "an inspiration for the ages", saying the charges he'd faced were "a modern form of crucifixion".

But Steve Dimopoulos - a government minister in Cardinal Pell's home state of Victoria - was among those who voiced mixed feelings.

"Today would be a very difficult day for the cardinal's family and loved ones, but also very difficult for survivors and victims of child sexual abuse and their families and my thoughts are with them," he said.

The cardinal was a polarising figure, both in Australia and abroad, something he himself conceded.

He rose to prominence in the Church as a strong supporter of traditional Catholic values, often taking conservative views and advocating for priestly celibacy.

Speaking to the BBC in 2020, Cardinal Pell said there was "no doubt" that his "direct" style and traditional approach to issues such as abortion had driven parts of the public against him.

"The fact that I defend Christian teachings is irritating to a lot of people," he told BBC Radio 4's Sunday programme.