The editor of the Vatican's daily newspaper has been accused of engineering a dirty tricks campaign against a rival with false accusations of a gay affair and harassment.
The alleged plot has been revealed in a controversial new book that portrays the Vatican as a hotbed of jealousy, intrigue and underhanded factional fighting.
His Holiness - The Secret Papers of Benedict XVI is based on hundreds of letters, memos and diplomatic cables that were leaked by Vatican whistle-blowers, including one code-named "Maria".
One of the most intriguing claims is that Gian Maria Vian, the editor of L'Osservatore Romano, leaked false documents which purported to show that Dino Boffo, the editor of another Roman Catholic newspaper, L'Avvenire, had had a homosexual affair with a man and harassed his wife.
The furor over the claims, which erupted in 2009, forced Mr Boffo to resign. He always maintained his innocence and the documents were later shown to be false.
The accusation that they were leaked to the mainstream press was made by Mr Boffo himself. Months after the scandal, he wrote to the Pope's private secretary claiming that he had found out that Mr Vian had leaked the false dossier.
He speculated that it was part of a power play within the Catholic hierarchy.
While Mr Vian has not publicly commented on the accusations, the Vatican has jumped to his defence, saying that he had nothing to do with the affair. The allegations were "spurious and groundless", it said in a statement, adding that the Pope "deplores these unjustified and offensive attacks".
The Vatican has condemned the publication of the book, written by Gianluigi Nuzzi, an Italian journalist, as "a criminal act", saying that confidential documents were "stolen" from the Pope in a violation of his privacy.
The Pope recently appointed a commission of cardinals to find the person or people responsible for leaking the papers, some of which allege corruption and nepotism in the awarding of contracts in the city state.
Other leaked documents cited in the book purportedly show that just before Christmas last year, one of Italy's best known television presenters, Bruno Vespa, sent a cheque for euros 10,000 (pounds 8,000) to the Pope as a charitable donation - and asked for a private audience with "the Holy Father" in return.
It is not clear if the request was granted, but the Pope's personal secretary made a note to discuss it with his boss.