France and Mexico have angrily demanded prompt explanations from the United States following "shocking" new spying allegations leaked by former US security contractor Edward Snowden.
The reports published in French daily Le Monde and German weekly Der Spiegel reveal that the US National Security Agency secretly monitored tens of millions of phone calls in France and hacked into then Mexican president Felipe Calderon's e-mail account.
They come on top of revelations leaked by Snowden and published in June that the US had a vast, secret programme called Prism to monitor internet users.
French Prime Minister Jean-Marc Ayrault said he was "deeply shocked" by the revelations and demanded an explanation from US authorities.
"It's incredible that an allied country like the United States at this point goes as far as spying on private communications that have no strategic justification, no justification on the basis of national defence," he told journalists on a trip to Copenhagen.
French Foreign Minister Laurent Fabius said the US ambassador had been summoned to his ministry for a meeting.
The US embassy in Paris refused to comment on "alleged intelligence activities" but said ambassador Charles Rivkin had promised to convey France's concerns back to Washington.
The spy agency monitored 70.3 million phone calls in France over a 30-day period between December 10 and January 8 this year, Le Monde reported, citing documents from Snowden.
According to the paper, the NSA automatically picked up communications from certain phone numbers in France and recorded certain text messages under a programme code-named "US-985D".
Le Monde said it gave grounds to believe that the NSA targeted not only people suspected of being involved in terrorism but also high-profile individuals from the business world or politics. US officials declined comment to the French daily.
The Le Monde article followed revelations by Der Spiegel - also based on documents provided by Snowden - that US agents had hacked into the Mexican presidency's network, gaining access to Calderon's account.
According to the report, the NSA reportedly said the president's office was now "a lucrative source" of information."This practice is unacceptable, illegitimate and contrary to Mexican law and international law," Mexico's foreign ministry said.
Snowden, who has taken refuge in Russia, is wanted in the US for espionage after leaking details of the NSA's snooping activities. The fugitive had been in hiding in Hong Kong from May to June 23, when he flew to Moscow, where he stayed in an airport transit area for over a month before being given temporary asylum.