Italian investigative journalist Gianluigi Nuzzi has been summoned for questioning next Wednesday at the Vatican over his explosive new tell-all Merchants in the Temple, Nuzzi said on his Facebook page.
"I am evaluating my course of action and will let you know. I am not worried," Nuzzi wrote.
Nuzzi and Italian journalist Emiliano Fittipaldi, who also published an expose this month alleging malfeasance at the Holy See are under investigation, the Vatican said earlier this week.
Both Nuzzi and Fittipaldi have refused to reveal who leaked documents to them used in their books, which depict a Vatican plagued by corruption, mismanagement, greed, cronyism and lavish spending.
A Vatican statement on 2 November, however, appeared to link the new books to the arrest of high-ranking Spanish priest Monsignor Lucio Angelo Vallejo Balda and an Italian laywoman, PR consultant Francesca Chaouqui.
Both Vallejo Blada and Chaoqui are former members of a commission set up by Francis in 2013 to study Vatican financial reforms.
The arrests and books mark a new phase in the so-called 'Vatileaks' scandal. It began in 2012 when Pope Benedict XVI's butler was convicted on charges he supplied Nuzzi with stolen documents for his earlier Vatican expose, the best-selling His Holiness.
The stolen private letters between Benedict and his private secretary disclosed venomous infighting at the top of the Catholic Church and serious graft allegations in the Vatican government.