French President François Hollande, one of the three leaders suspected to have been spied on by the US National Security Agency (NSA), has called an emergency defence council meeting following explosive WikiLeaks revelations.
Hollande will chair the meeting shortly but the agenda is unclear.
The whistleblower website has leaked "top secret" NSA files from the collection of surveillance data labelled "Espionnage Elysée" (Elysée Spy).
Elysée Palace said the French authorities would look into "what is involved" in the disclosures.
It was also claimed that French cabinet ministers and Paris's ambassador to the US have been the targets of surveillance.
Michele Alliot-Marie, France's former defence and foreign minister, told iTele TV: "We are not naive, the conversations that took place between the defence ministry and the president did not happen on the telephone. That being said, it does raise the problem of the relationship of trust between allies."
The files first trickled out via the French daily Libération and the investigative news website Mediapart. According to the disclosed documents, the NSA listened to and recorded the telephone conversations of at least three successive French presidents between 2006 and 2012.
Responding to the allegations, National Security Council spokesperson Ned Price said: "We are not targeting and will not target the communications of President Hollande ... we work closely with France on all matters of international concern, and the French are indispensable partners."
A statement from WikiLeaks founded by Julian Assange said: "The French people have a right to know that their elected government is subject to hostile surveillance from a supposed ally. French readers can expect more timely and important revelations in the near future."