Five people are set to go on trial in the Vatican accused of leaking and publishing secret documents revealing mismanagement in the Holy See.
Two journalists who cited the documents in two books will face the tribunal, along with two members of a papal commission and an assistant.
If convicted, they could be jailed for up to eight years.
Media groups have condemned the trial. One of the journalists charged called it “an attack on press freedom”.
The journalists, Emiliano Fittipaldi and Gianluigi Nuzzi, carried allegations of the misuse of charitable and other funds in their books Merchants in the Temple and Avarice.
The allegations included the lavish refurbishment of apartments for cardinals and others.
The three accused of leaking the documents are a Spanish priest and an Italian public relations expert who sat on a commission which advised the Pope on economic reform, along with the priest’s secretary.
Media groups have urged the Vatican to drop the charges.
Nina Ognianova, of the Committee to Protect Journalists, said: “Journalists should be allowed to carry out their role as watchdog and investigate alleged wrongdoing without fear of repercussions.”
The journalists involved called the trial “Kafka-esque”, saying neither they or their lawyers had seen details of the charges.
Mr Fittipaldi said: “This is a trial against freedom of the press. In no other part of the world, at least in the part of the world that considers itself democratic, is there a crime of a scoop, a crime of publishing news.”
BBC religious affairs correspondent Caroline Wyatt says the rapidity with which the Vatican has moved to charge the five stands in sharp contrast to the length of time it has taken to help bring many priests accused of child sex abuse to trial.
She adds that if long sentences are passed on the journalists, the Vatican would have no facilities for holding the inmates and would have to ask Italy – where freedom of the press is protected – to extradite and then lock them up on a charge that is not a crime there.
The three accused of leaking the documents are Msgr Angelo Lucio Vallejo Balda and his assistant Nicola Maio, along with PR expert Francesca Chaouqui.
The special reform commission they were serving was set up by Pope Francis to tackle the Vatican’s financial holdings and propose reforms to improve cash flow to the poor.