Hackers raised the temperature of refrigerators and freezers ​at hundreds of French supermarkets to as high as 50 degrees Celsius (122 degrees Fahrenheit), causing fires and spoiling food.

The Paris prosecutor’s office said on Monday ‌that a “large-scale” attack was “affecting connected refrigerators in several major food retailers across France,” leading to food losses and fires. CNN reported.

Prime Minister Sebastien Lecornu has instructed France’s National Cybersecurity Agency (ANSSI) to investigate, a person in his office said.

France was coordinating with European counterparts because other countries could also be affected, the person said, adding that authorities were assessing whether other French companies were at risk.

Felix Aime, a senior cyber threat intelligence analyst at Sekoia Threat Detection and Research, said Spain, Portugal, Poland, Germany and Belgium had also been affected.

Carrefour said 80 of its supermarkets were hit, while Monoprix, which operates about 490 stores in France, said 5 per cent of its stores were affected.