Several major companies said Tuesday they were targeted in an international cyberattack which started in Russia and Ukraine before spreading to western Europe.

Danish sea transport company Maersk, British advertising giant WPP and the French industrial group Saint-Gobain all said they came under attack and put protection protocols in place to avoid data loss.

"Most of our IT systems are down across all business units due to a virus. We continue to assess the situation. The safety of our operations are top of our priorities," Concepcion Boo Arias, spokeswoman of Maersk Line, told AFP.

A Saint-Gobain spokesperson told AFP that the company also "is the target of a cyberattack. As a security measure we have isolated our computer systems to protect our data".

WPP tweeted that "IT systems in several WPP companies have been affected by a suspected cyber attack. We are taking appropriate measures & will update asap".

The three groups were the first major businesses to be hit by what is believed to be a ransomware attack of the so-called Petya type, which earlier affected Russia and Ukraine.

"This is a bit like a flu epidemic in winter," said Nicolas Duvinage, head of the French military's digital crime unit.

"We will get many of these viral attack waves in coming months," he said.