A trial has opened in Vatican City of 10 defendants, including a once-powerful cardinal, in a case based on a widespread probe into the allegedly criminal management of the Holy See’s portfolio of assets, including donations by countless Catholic worshippers.

Among the defendants is Italian prelate Angelo Becciu, a veteran Vatican diplomat whom Pope Francis raised to the rank of cardinal in 2018.

After a web of scandals started unravelling during a two-year investigation, Francis last year sacked Becciu as chief of the Catholic Church’s saint-making office. Not waiting for find out the eventual verdict of a Vatican court, he also removed Becciu’s rights as a cardinal.

Less than three months ago, it would have been impossible for a cardinal to be in the dock in Vatican City State, which has its own justice system and even a jail. But Francis had a Vatican law changed so that Vatican-based cardinals and bishops can be prosecuted and judged by the Holy See’s lay criminal tribunal as long as the pontiff signs off on that. Previously, Vatican cardinals could only be judged by their peers, a court of three fellow cardinals.

Becciu, 73, is charged with embezzlement and with pressing a monsignor to recant information he supplied to prosecutors about the handling of the disastrous Vatican real estate investment in London. He has denied any wrongdoing.

Vatican prosecutors have alleged a jaw-dropping series of scandals (Gregorio Borgia/AP)

Since a nearly 500-page indictment was issued in early July, prosecutors have filed some 30,000 pages of supplemental documentation.

Defence lawyers say they have not had sufficient time to study the material.

The presiding judge, Giuseppe Pignatone, is a retired chief prosecutor of Rome who earlier in his career took on the Mafia and economic wrongdoing in Sicily.

To accommodate the largest criminal trial in the Vatican’s modern history, the hearings are being held in a large hall converted into a courtroom in the Vatican Museums.

A pool of reporters accredited with the Vatican is being allowed to follow the proceedings in court, but their accounts cannot be filed until after the day’s hearing ends.

The defendants are alleged to have had various roles in actions that effectively cost the Holy See tens of millions of dollars in donated funds through poor investments, dealings with shady money managers and purported favours to friends and family.

Looming large in the indictment is the London deal approved by the Vatican secretariat of state.

An initial 200 million euros (£171 million) was sunk into a fund operated by an Italian businessman. Half of that money went into the real estate venture in London’s upmarket Chelsea area, an investment which eventually cost 350 million euros (£300 million). By 2018, the original investment was losing money, and the Vatican scrambled to find an exit strategy.

Defendants include Cecilia Marogna, a former chief of staff in the Vatican secretariat of state, who was hired by Becciu as an external security consultant. Prosecutors allege she embezzled 575,000 euros (£491,695) in Vatican funds that Becciu had authorised for use as a ransom to free Catholic hostages abroad.

Marogna has contended that charges she ran up were reimbursement of her intelligence-related expenses and other money was her compensation.