France has summoned the US ambassador to explain why American spies secretly checked millions of French phone records.
The Le Monde newspaper says documents leaked by Edward Snowden show that the US National Security Agency swept up 70.3 million French phone records in a 30-day period.
The report, co-written by Glenn Greenwald who originally revealed the NSA surveillance programme, found that when certain numbers were used, the conversations were automatically recorded. The surveillance operation also swept up text messages based on key words, Le Monde reported.
Similar programmess have been revealed in Britain and Germany.
French Foreign Minister Laurent Fabius said he would demand an explanation for a practice he described as "totally unacceptable."