U.S. intercepts French phone calls on a 'massive scale' NSA leaker Edward Snowden NEW: France summons U.S. ambassador over spying allegations Le Monde: The NSA intercepted more than 70 million French phone calls over 30 days A weekend report said the NSA "systematically" eavesdropped on the Mexican government (CNN) -- France has summoned the U.S. ambassador to France over allegations that the National Security Agency intercepted more than 70 million phone calls in France over a 30-day period. I have immediately summoned the American ambassador. He will be at the Foreign Ministry this very morning," French Foreign Minister Laurent Fabius told reporters at an EU foreign ministers meeting in Luxemburg on Monday. U.S. Secretary of State John Kerry was also in Paris Monday for a previously scheduled meeting. The National Security Agency monitored and tapped the phone calls made in France, French newspaper Le Monde reported Monday, citing documents leaked by former NSA contractor Edward Snowden. "Telephone communications of French citizens are intercepted on a massive scale," Le Monde said in its online English edition. The snapshot of American espionage took place from December 10, 2012, to January 8, 2013, the article reported. An NSA graph shows an average of 3 million data intercepts a day. According to Le Monde, this is how the system worked: "When a telephone number is used in France, it activates a signal which automatically triggers the recording of the call. Apparently this surveillance system also picks up SMS (text) messages and their content using key words. Finally, the NSA apparently stores the history of the connections of each target -- or the meta-data. It wasn't immediately clear from the article if the conversations were being recorded or just the data surrounding each call. CNN reached out to France's Foreign Ministry for comment but did not hear back early Monday morning. The report comes a day after the German news magazine Der Spiegel said the NSA "systematically" eavesdropped on the Mexican government. It hacked the public e-mail account of former Mexican President Felipe Calderon, which was also used by Cabinet members, according to Der Spiegel. The magazine also quoted documents leaked by Snowden.