A suspected cyber attack has forced supermarket freezers to overheat across Sweden, Belgium and Ireland, spoiling food worth millions of euros just weeks after French retailers were hit by a near identical breach.

Freezers at Ica and Coop shops in Sweden were turned up to as high as 55C on Monday. Equipment in supermarkets run by Ahold Delhaize and Carrefour in Belgium and in stores operated by the Irish retailer Supervalu, were also affected. The pattern matches the earlier French case, with cooling units heated up overnight and fresh and frozen stock spoiling before staff noticed.

Ahold Delhaize, the Dutch retailer that owns chains across Europe, said fridges and freezers in dozens of its supermarkets in Belgium and Luxembourg had been hit. The Belga news agency reported overnight temperature increases at dozens of the company’s stores in both countries.

The incidents follow an attack in France last month in which hackers seized control of cooling units in as many as 700 supermarkets, raising their temperatures as high as 50C (122F) and causing fires and food losses estimated in the tens of millions of euros. In one French fridge, the temperature rose to 80°C.

That attack targeted refrigeration management software and disrupted hundreds of French supermarkets, with fridges and freezers forced to heat up remotely overnight. It appears to have exploited the window created by normal overnight defrost cycles, during which freezer temperatures rise briefly, pushing units well beyond safe thresholds before anyone noticed.

The chief executive of Coopérative U described the French attack as “extremely serious and unprecedented”, with more than 100 of the chain’s stores targeted.

Ahold Delhaize is no stranger to such breaches. The company reported a cyber security incident to police in the Netherlands in October after detecting suspicious activity in its infrastructure.