A secretly recorded telephone call between embattled Cardinal Angelo Becciu and Pope Francis has been played in court at a Vatican corruption trial.
The recording was made without the Pope's knowledge by someone in a room with Becciu in July 2021, shortly before the trial began and while the Pope was still recovering from major intestinal surgery, the court was told.
Reporters were asked to leave the room while the tape was played but lawyers who heard it said Becciu asked the Pope to confirm he had authorised a payment to help release a nun who had been kidnapped in Africa.
The lawyers said the Pope seemed perplexed and confused on the call by why Becciu was calling and that the pontiff repeatedly asked the cardinal to send him a written note about what he wanted.
In 2018, Becciu, then the third most powerful person in the Vatican, hired co-defendant Cecilia Marogna, a self-styled security analyst, to free a Columbian nun kidnapped in Mali by an al Qaeda-linked group.
Marogna, 44, received 575,000 euros ($A885,045) from the Secretariat of State, the Vatican's most important department, in 2018 to 2019 when Becciu was working there.
The money was sent to a company she had set up in Slovenia and she received some in cash, the court has been told.
The police discovered Marogna had spent much of the money for personal use, including luxury brand clothing and visits to health spas.
She is charged with embezzlement and Becciu is charged with embezzlement, corruption and abuse of office.
They and the other eight defendants have denied all wrongdoing.
The chief prosecutor at the trial, Alessandro Diddi, told reporters on Thursday he had begun a new tangent of his investigation in which he suspects Becciu of criminal conspiracy.
He said he deposited the details with the court.
Becciu's lawyers said in a statement they were not aware of any new accusations. The statement did not comment on the secretly recorded phone call.
A year before the trial started, Francis fired Becciu on suspicion of nepotism. Becciu denies doing anything to help his family financially.
On Thursday, Becciu faced his main accuser, his former top aide Monsignor Alberto Perlasca.
Perlasca told the court how he was ordered to make payments he considered unusual.
He said he sent 100,000 euros to a charity in Sardinia, not knowing at the time that it was linked to Becciu's family.
Becciu has said the charity helped create jobs in a poor area.
The trial revolves around the purchase of a building in London by the Secretariat of State.
The 10 defendants include former Vatican employees and Italian middlemen who the prosecution says extorted the Vatican.