Top secret documents concerning Britain's multi-million pound deal to develop state-of-the-art drones with France have been stolen in Paris, an incident that had all the hallmarks of a covert operation by spies, a media report said.
Two men are believed to have stolen a briefcase at the Gare du Nord station in Paris.
A high-level executive working for French company Dassault Aviation was on his way to London on the Eurostar train on February 2 when the theft took place, The Daily Mail reported.
As per the media report, the unnamed man briefly left his case unattended when his female colleague was "hassled" by a stranger, a Paris Judicial Police source said.
Documents in the case were marked "Defence - Confidential" and contained details of the Franco-British drone project, a legal source close to the case told Le Parisien newspaper.
The report quoted the source as saying that the theft happened at around 5pm, when the station was packed with cross-Channel travellers.
When the Dassault executive returned to a self-service ticket machine after helping his colleague 'his briefcase had disappeared'.
The source said: "His attention had been purposefully diverted. It was not a random theft. We have to determine whether the thieves were targeting confidential documents on the drone project or other valuables in the briefcase".
While the police insisted that a highly-sophisticated operation by a spy agency could not be ruled out, Dassault said it was "probably a random theft", the report said.
The company confirmed that a briefcase belonging to an employee was taken, but insisted that it did not contain any "sensitive documents".
"It was basically a petty theft, like so many others at the station", a Dassault spokesman was quoted as saying who added that the incident was captured on security cameras
France and UK plan to develop a new generation of fighter drones and is their biggest collaboration since they agreed to closer military cooperation last year.