The National Security Agency (NSA) allegedly eavesdropped on cardinals of the Roman Catholic Church -- including then-Cardinal Jorge Bergoglio, now Pope Francis -- before the conclave in March in which Francis was elected, Italian magazine Panorama claimed Wednesday.
"The National Security Agency wire-tapped the pope," the magazine said, accusing the United States of listening in to telephone calls to and from the Vatican.
The allegations follow a report on surveillance website, Cryptome, which said the U.S. intercepted 46 million telephone calls in Italy in December last year and early January this year.
Among those, "there are apparently also calls from and to the Vatican," Panorama said.
The latest spying claims come amid a huge diplomatic row over the revelation that the NSA tapped the phone records of millions were tapped in many countries across Europe that included several heads of the state.
Germany's top foreign affairs and intelligence advisors are in the U.S. to hold talks after it emerged that Chancellor Angela Merkel's phone was bugged by the NSA.
On Monday, Spain summoned the US ambassador to discuss alleged spying on its citizens and said that, if true, the action was unacceptable behavior by an ally.
The Italian magazine added that before Francis became pope, he "had been a person of interest to the American secret services since 2005, according to Wikileaks."
The bugged conversations were divided into four categories: "leadership intentions," "threats to financial systems," "foreign policy objectives" and "human rights," it claimed.
Vatican spokesman Federico Lombardi said "we have heard nothing of this and are not worried about it."
If true, the U.S. spying would be an embarrassing blow to an institution famous for its secrecy.
The goings-on of the conclave are particularly cloak-and-dagger, with a system installed in the Sistine chapel where the cardinals meet in order to scramble any mobile phone communications and excommunication for those who attempt to spill the beans.