VATICAN CITY (AP) — The Vatican on Saturday denounced as “criminal” a new book of leaked internal documents that shed light on power struggles inside the Holy See and the thinking of its embattled top banker, and warned that it would take legal action against those responsible.

Pope Benedict XVI has already appointed a commission of cardinals to investigate the “Vatileaks” scandal, which erupted earlier this year with the publication of leaked memos alleging corruption and mismanagement in Holy See affairs and internal squabbles over its efforts to comply with international anti-money laundering norms.

The publication Saturday of “His Holiness,” by Italian journalist Gianluigi Nuzzi, added fuel to the fire, reproducing confidential letters and memos to and from Benedict and his personal secretary which, according to the Vatican, violated the pope’s right to privacy.

Vatican spokesman the Rev. Federico Lombardi said in a statement Saturday the book was an “objectively defamatory” work that “clearly assumes characters of a criminal act.” He said the Holy See would get to the bottom of who “stole” the documents, who received them and who published them. He warned the Holy See would seek international cooperation in its quest for justice, presumably with Italian magistrates.

The Vatican had already warned of legal action against Nuzzi after he broadcast letters in January from the former No. 2 Vatican administrator to the pope in which he begged not to be transferred for having exposed alleged corruption that cost the Holy See millions of euros in higher contract prices. The prelate, Monsignor Carlo Maria Vigano, is now the Vatican’s U.S. ambassador.

Nuzzi, author of “Vatican SpA,” a 2009 volume laying out shady dealings of the Vatican bank based on leaked documents, said he was approached by sources inside the Vatican with the trove of new documents, most of them of fairly recent vintage and many of them painting the Secretary of State, Cardinal Tarcisio Bertone, in a negative light.