France summoned the U.S. ambassador on Monday to protest allegations in Le Monde newspaper about large-scale spying on French citizens by the U.S. National Security Agency.
The allegations that the agency was collecting tens of thousands of French telephone records risked turning into a diplomatic row just as U.S. Secretary of State John Kerry arrived in Paris for the start of a European tour over Syria.
"I have immediately summoned the U.S. ambassador and he will be received this morning at the Quai d'Orsay (the French Foreign Ministry)," French Foreign Minister Laurent Fabius told reporters on the sidelines of an EU meeting in Luxembourg.
Earlier, France's interior minister, Manuel Valls, said Le Monde's revelations that 70.3 million pieces of French telephone data were recorded by the NSA between Dec 10, 2012 and Jan 8, 2013 were "shocking."
"If an allied country spies on France or spies on other European countries, that's totally unacceptable," Valls told Europe 1 radio.
U.S. Ambassador to France Charles Rivkin declined immediate comment on reports that he had been called in by the French foreign ministry but stressed that U.S.-French ties were close.
"This relationship on a military, intelligence, special forces ... level is the best it's been in a generation," Rivkin told Reuters as Kerry arrived in Paris.
In July, Paris prosecutors opened a preliminary inquiries into the NSA's programme, known as Prism, after Germany's Der Spiegel and Britain's The Guardian revealed wide-scale spying by the agency leaked by former NSA contractor Edward Snowden.
"We were warned in June (about the programme) and we reacted strongly but obviously we need to go further," Fabius said. "We must quickly assure that these practices aren't repeated."
The NSA's targets appeared to be individuals suspected of links to terrorism, as well as those tied to French business or politics, Le Monde wrote.