The US National Security Agency (NSA) and UK counterpart GCHQ have been working on intercepting data from passengers' cell phones on commercial airlines including Air France since 2005, France's Le Monde newspaper has reported.

Air France was among the first airlines to be targeted by projects belonging to the two spy agencies after it carried out tests on allowing the use of mobile phones in the air in 2007. At the time, this was not a common practice, though some 100 companies now do permit it.

The French airline was seen as a prominent terrorist target by both national security agencies.

Snowden is a hero to some, a traitor to others

"The use of mobile phones with internet connections in the sky gave rise to the creation of specific programs at the NSA and GCHQ," Le Monde wrote in its report.

The paper, in partnership with news website "The Intercept," has access to the archive of documents gathered by former NSA contractor Edward Snowden, who in 2013 leaked masses of classified information on the US surveillance of private data to the press.

'Thieving Magpie'

The spy projects, codenamed "Thieving Magpie" and "Homing Pigeon," could collect data from telephones used on aircraft if the planes were flying at an altitude of more than 10,000 feet, the report said. The signals were picked up by secret interception stations on the ground as they transited through a satellite.

"The simple fact that the telephone was switched on was enough to give away its position. The interception could then be cross-referenced with the list of known passengers on the flight, the flight number and the airline code to determine the name of the smartphone user," Le Monde said.

The report said that GCHQ and NSA provided several individual examples of calls intercepted on board commercial flights in the documents.

Although it is normally not possible to make phone calls on planes, some airlines allow users to access internet-based functions via a cabin Wi-Fi system.

Snowden now lives in Moscow under an asylum deal following his leaks of the classified material, which provoked an international furor at the extent of the US' collection of private data in the wake of the September 11, 2001 terrorist attacks.

If he were to return to the US, he would face up to 30 years in prison on espionage and other charges.

tj/kms (Reuters, AFP)