The trial, in which three Vatican insiders and two Italian reporters face potential prison terms of up to eight years, was adjourned until next week after one of the accused asked for more time to prepare her defence.
Francesca Chaouqui, a PR expert accused of leaking classified documents to journalists, asked for five days to study the prosecution case against her and possibly introduce new evidence after replacing her court-appointed lawyer with her own defence counsel.
The prosecution did not object and the presiding judge said proceedings would resume on December 7, dashing the hopes of Vatican officials that the high-profile case might be wrapped up before the official start of a Catholic Jubilee year the following day.
Pope Francis, who has been away on a visit to Africa, told journalists on his return flight to the Vatican on Monday that the leaks scandal "has not kept me awake at night".
"This isn't the Lucrezia Borgia era," he quipped in a reference to the daughter of Pope Alexander VI in the 15th century, who was accused of incest, poisoning and murder.
It emerged on Monday that Chaouqui's co-accused, Spanish Monsignor Lucio Vallejo Balda, 54, wrote a statement six days after his arrest in which he admitted to having been sorely tempted to have an affair with Chaouqui, 33, and that he believed she was working for Italy's secret services.
According to Italian daily La Repubblica, the statement was made on November 8th to a lawyer no longer working for Vallejo Balda.
Several Italian media have reported that the priest's new counsel plans to ask the court for his client to undergo psychiatric evaluation - implying he may seek to put forward mental issues as a mitigating factor in his defence.
'No proof against me'
There was no time for that on Monday as a result of Chaouqui's delay request, which she said was necessary because she still had no idea of what she was supposed to have done wrong.
"I don't understand anything," she told reporters after the brief hearing.
"There is no proof against me. I need this extra time to understand why I am here."
The Vatican has been widely criticised for pursuing the prosecution of two investigative journalists, Gianluigi Nuzzi and Emiliano Fittipaldi, over leaks they used as the basis for books depicting irregularities and extravagance in the Holy See's spending.
Chaouqui had access to potentially embarrassing material after being asked to join a commission on economic reform set up by Pope Francis shortly after his election in 2013.
The appointment raised eyebrows at the time after it was revealed Chaouqui had published critical tweets about the Vatican and posted racy pictures of herself on social media.
Vallejo Balda was secretary to the commission. His assistant Nicola Maio is the fifth person charged under legislation the Vatican introduced in reaction to the first Vatileaks scandal.
That erupted in 2012 and involved former pope Benedict XVI's butler revealing the extraordinary scale of bitter infighting in the upper echelons of the Church's bureaucracy, the curia.
'I couldn't succumb'
All five accused in Vatileaks II have been charged with obtaining and disclosing confidential papers "concerning the fundamental interests of the Vatican State".
Vallejo Balda, who has been in detention since his November 2nd arrest, Chaouqui and Maio are additionally charged with organised criminal association.
In the statement published by La Repubblica, the priest suggests his relationship with Chaouqui was of a romantic, flirtatious nature and came close to being consummated.
"I could not succumb, in my mind's eye I always had the pope talking about the sanctity of married women and marriage," the priest reportedly wrote.
He goes to claim that Chaouqui had assured him her marriage was a cover for her real role as a spy.
"She sent me photos of (him) with another woman whom she said was his real wife," the statement reads.
Chaouqui said in a post on her Facebook page last week that she is pregnant and very happy with her partner.