VATICAN CITY  (Reuters) - An Italian magazine reports that a United States spy agency had eavesdropped on Vatican phone calls, possibly including when former Pope Benedict's successor was under discussion, but the Holy See said it had no knowledge of any such activity.

Panorama magazine said Wenesday that among 46 million phone calls followed by the U.S. National Security Agency (NSA) in Italy from Dec. 10, 2012, to Jan. 8, 2013, were conversations in and out of the Vatican.

In a press release before full publication on Thursday, Panorama said the "NSA had tapped the Pope." It cited no source for its information.

Asked to comment on the report, Vatican spokesman Father Federico Lombardi said: "We are not aware of anything on this issue and in any case we have no concerns about it."

Media reports based on revelations from Edward Snowden, the fugitive former U.S. intelligence operative granted asylum in Russia, have said the NSA had spied on French citizens over the same period in December in January.

Last week, the German government appeared to confirm that Chancellor Angela Merkel's cell phone had also been monitored by American spies. The issue has also caused Washington problems with Brazil and China.

Panorama said the recorded Vatican phone calls were catalogued by the NSA in four categories - leadership intentions, threats to the financial system, foreign policy objectives and human rights.

Benedict resigned on Feb. 28 this year and his successor, Pope Francis, was elected on March 13.

"It is feared" that calls were listened to up until the start of the conclave that elected Francis, the former Cardinal Jorge Mario Bergoglio of Argentina, Panorama said.

The magazine said there was also a suspicion that the Rome residence where some cardinals lived before the conclave, including the future Pope, was monitored.

(Reporting by Steve Scherer; Editing by Philip Pullella and Angus MacSwan)