Worldwide cyberattack hits French rail operator, Saint-Gobain

France's national rail operator, the Saint-Gobain building supply company and supermarket chain Auchan are among hundreds of companies worldwide hit by Wednesday's Petrwrap ransomware. French police have launced an inquiry into the massive cyberattack.

An IT researcher with a screen infected by a ransomware at the LHS (High Security Laboratory) In Rennes Damien Meyer/AFP

French rail company SNCF said its services were not affected by the attack, while Saint-Gobain said on Wednesday morning that the problem was being dealt with.

"As a security measure, so as to protect our data, we have isolated our computer systems," a company spokesman said.

The attacks started in Russia and Ukraine, hitting dozens of firms, including Russian oil giant Rosneft and the Chernobyl nuclear reactor.

They have also hit the Maersk maritime transporter, the Nivea company in Germany and Merck pharmaceutical labororatory in the US.Specialists say the Petrwrap virus is a modified version of the Petya ransomware that hit systems last year.

French police open inquiry

Last month the Wannacry virus hit more than 300,000 computers around the world, including the Renault carmaker in France.

"The level of this attack is unprecedented," French Digital Affairs Minister Mounir Mahjoubi said on Wednesday.

French police called for vigilance in respect to a "new version of Petya optimised by Wannacry".

The cyberpolice brigade OCLCTIC has opened an inquiry and issued a statement on social media warning that the virus can hit all versions of Windows software and recommending that people do not pay the ransom demand.