image copyrightReutersimage captionCardinal Giovanni Angelo Becciu (L) had been a close adviser to Pope Francis

A Roman Catholic cardinal who was once a close ally of Pope Francis is going on trial in the Vatican, accused of misusing Church funds in a ruinous London property venture.

Cardinal Angelo Becciu, 73, is the most senior cleric in modern times to face trial for alleged financial crimes.

He is charged with spending €350m (£299m; $412m) of church money on a botched deal to buy a property in Chelsea that incurred huge losses.

He denies wrongdoing.

Nine other defendants are also accused of charges including extortion, embezzlement and abuse of office.

Cardinal Becciu was sacked by the Pope in September, as reports of financial misdeeds emerged.

A two-year investigation exposed how the Vatican lost millions of euros, including donations from worshippers, after buying a prestigious former Harrods warehouse in Sloane Avenue, Chelsea, in 2014. The cardinal was formerly in charge of donations at the secretariat which handles Vatican funds.

The charges against him include allegedly channelling money to businesses run by his brothers in their native Sardinia.

The trial is expected to last for months. The two hearings this week – on technical matters – are likely to be adjourned until October. The nine others accused include:

  • Swiss lawyer René Brülhart, who previously headed the Vatican's financial regulation body, the former Financial Information Authority, and his ex-deputy Tomasso di Ruzza
  • Monsignor Mauro Carlino, who was Cardinal Becciu's private secretary
  • Enrico Crasso, a former Vatican investment manager
  • Cecilia Marogna, accused of buying luxury goods with funds authorised by the cardinal for Vatican intelligence work, including efforts to free clergy held hostage in various countries.

The defendants deny wrongdoing. If found guilty, they could face jail terms or fines, or both.

Prosecutors allege that a London-based broker, Gianluigi Torzi, defrauded the Vatican while using its money to buy shares in the Chelsea building, which was to be converted into luxury apartments. Mr Torzi says the allegations are based on a misunderstanding. Italy is trying to get him extradited from the UK.

The Vatican's new finance chief, Juan Antonio Guerrero, has said the Vatican is now making unprecedented efforts to be transparent about its financial affairs.

On 24 July the Vatican for the first time published details of its investment portfolio: 4,051 properties in Italy and some 1,120 properties in London, Paris, Geneva and Lausanne.

"We come from a culture of secrecy, but we have learned that in economic matters transparency protects us more than secrecy," Fr Guerrero said.