A Spanish priest, Fr Vallejo Baldo, 54, and a PR guru are caught up in accusations of sexual encounters and spying for the Italian secret services.
Francesca Chaouqui, a public relations officer, 33, was asked by Pope Francis to monitor the Vatican. She has said she is suing Father Lucio Angel Vallejo Baldo, her former committee member, after it was reported that he claimed she pushed him into have sex and boasted about being a spy.
According to The Times, Francesca Chaouqui said that: "Everything he stated is false and I have sued him for defamation.
"I doubt Father Vallejo Baldo would have slept with me because he does not go for women."
Both Mrs Chaouqui and Fr Vallejo Baldo as well as his former assistant Nocjola Maio, face up to eight years in prison if they are convicted by the Vatican court.
The three are all accused of leaking Vatican documents which alleges money mismanagement and Vatican waste.
Two Italian journalists, who published the information, are also on trial.
However a hearing on Monday was adjourned for a week after Mrs Chaouqui appointed a new lawyer.
On Monday Italian newspaper La Repubblica published a statement from Fr Vallejo Baldo which claimed that Mrs Chaouqui pressured him into handing confidential documents to journalists as well as accused her of making sexual advances.
It says: "I couldn't give in.
"I kept on seeing the Pope before me when he spoke of the sanctity of married women and marriage."
In December 2014 Fr Vallejo Baldo claimed that he had sex with Mrs Chaouqui.
He also claimed that she told him she was working for the secret services and that her marriage was a false front.
"She sent me photos of Corrado [her husband] with another woman, his real wife," he said in his statement.
Mrs Chaouaqui's husband said that the pair had been married 11 years and are expecting a child.
The priest's lawyer has asked for psychological testing for his client according to Italian media.
