“On the eve of the Olympics, this operation demonstrates that different players in France and abroad are mobilised to fight against all forms of cybercrime,” Paris chief prosecutor Laure Beccuau said in a statement.

She said investigators were targeting a network of bots suspected of infecting computers with PlugX malware and of stealing data from them “notably for purposes of espionage”.

She said analysts and investigators had managed to take control of a server that was controlling millions of the infected computers and were administering a fix.

They launched the operation on July 18th and it is expected to last several months, having already aided victims in several European countries, the statement said.

It did not cite a specific threat to the Paris Olympics. But separately, the French government’s cyber security agency warned last week that ransomware attacks will be “inevitable” during the Games, which officially open Friday.