The French government has summoned the US ambassador in Paris, demanding an explanation about claims that the National Security Agency has been engaged in widespread phone surveillance of French citizens, reports The Guardian.
On Monday, Le Monde published details from the NSA whistleblower Edward Snowden suggesting that the US agency had been intercepting phone calls on what it termed "a massive scale".
The French foreign minister, Laurent Fabius, warned: "This sort of practice between partners that invades privacy is totally unacceptable and we have to make sure, very quickly, that this no longer happens."
His summoning of the ambassador for urgent talks came as the US secretary of state, John Kerry, arrived in the French capital for the start of a European tour focused on discussions on the Middle East, especially Syria, and keen to stress Washington's close military and intelligence ties with Paris, which he recently called the "oldest ally" of the US.
The French interior minister, Manuel Valls, described the revelations as shocking and said he would be pressing for detailed explanations from Washington.
"Rules are obviously needed when it comes to new communication technologies, and that's something that concerns every country," he told Europe-1 radio. "If a friendly country – an ally – spies on France or other European countries, that is completely unacceptable."
The report in Le Monde, which carries the byline of the outgoing Guardian journalist Glenn Greenwald, who worked with Snowden to lay bare the extent of the NSA's actions, claims that between 10 December 2012 and 8 January 2013 the NSA recorded 70.3m phone calls in France.
According to the paper, the documents show that the NSA was allegedly targeting not only terrorist suspects but politicians, businesspeople and members of the administration under a programme codenamed US-985D.
"The agency has several collection methods," Le Monde said. "When certain French phone numbers are dialled, a signal is activated that triggers the automatic recording of certain conversations. This surveillance also recovers SMS and content based on keywords."
Such methods, it added, allowed the NSA to keep a systematic record of each target's connections.
Le Monde said the unpublished Snowden documents to which it had access showed "intrusion, on a vast scale, both into the private space of French citizens as well as into the secrets of major national firms".
The most recent documents cited by Le Monde, dated April 2013, indicated the NSA's interest in email addresses linked to Wanadoo, which was once part of France Telecom. About 4.5 million people still use wanadoo.fr email addresses in France.
Also targeted was Alcatel-Lucent, a French-American telecom company that employs more than 70,000 people and works in the sensitive sector of equipping communication networks. One of the documents instructed analysts to draw not only from the electronic surveillance programme but also from another initiative dubbed Upstream, which allowed surveillance on undersea communications cables.
Le Monde said US authorities had declined to comment on the documents, which they regard as classified material.
Instead, they referred the paper to a statement made in June by the US director of national intelligence, in which James Clapper defended the legality of the practices.
"[They] are lawful and conducted under authorities widely known and discussed, and fully debated and authorised by Congress," he said. "Their purpose is to obtain foreign intelligence information, including information necessary to thwart terrorist and cyber-attacks against the United States and its allies."
In July, Paris prosecutors opened a preliminary inquiry into the NSA's Prism programme, after the Guardian and Germany's Der Spiegel revealed wide-scale spying by the agency leaked by Snowden.
Read more of this report from The Guardian.