A cyberattack on French television network TV5 Monde may have been carried out by Russia-based backers

The “CyberCaliphate” attack that threatened French soldiers and shut down the Paris-based television network for hours was probably launched from computers in Russia, sources close to the investigation and TV5 Monde’s president said on Tuesday, confirming a report published by L’Express weekly.

The French magazine said clues pointed towards a group known as “Pawn Storm”, a term also used to refer to a multi-pronged attack in the computer hacking world.

The same group has previously targeted computer systems belonging to the While House, NATO members, Russian dissidents and Ukrainian activists, according to L’Express.

Messages in support of the Islamic State group were published on TV5 Monde’s website and on its social media accounts on the evening of April 8. The messages, published in English, French and Arabic, were threats against the families of French soldiers serving overseas.

TV5 Monde was forced to broadcast pre-recorded programmes after the hack, which it described as "unprecedented in the history of television".

However, investigators discovered that the computer codes used in the attack were typed out on a Cyrillic keyboard during office hours in Moscow and St. Petersburg, L’Express wrote this week.

At the time of the cyberattack two months ago, FRANCE 24's Wassim Nasr, an expert on jihadist movements, expressed doubt over the authenticity of the attack’s links to the IS group, noting that messages in Arabic contained plenty of spelling and grammar mistakes.

Relations between France and Russia have been strained amid the ongoing armed conflict in eastern Ukraine and European sanctions against Moscow. Paris has recently decided not to deliver two Mistral warships that were ordered by Russia’s navy.