Refrigerators and freezers at several Swedish supermarkets heated up overnight into Monday, leaving stores with spoiled food and raising suspicions of a cyberattack.
Grocery chains ICA and Coop confirmed that some of their locations were affected, Reuters reported .
One of the affected stores, ICA Kvantum in Sjöbo, southern Sweden, said on Facebook that hackers had broken into its cooling systems and set the temperature of its refrigerators and freezers to 50°C.
The store closed for the morning before reopening later in the day, according to Swedish public broadcaster SVT.
ICA confirmed that a limited number of its stores had experienced problems overnight, but did not say how many were affected or confirm that hackers were responsible.
The company said it was investigating the cause and supporting the stores involved. Coop, meanwhile, reported similar problems at six of its stores in central Sweden, SVT reported.
The incidents were spread across several parts of the country, including the southern region of Skåne and the island of Öland. At an ICA Nära store in Böda, on Öland, the manager arrived to find water covering the floor and a freezer showing a temperature of 55°C, according to SVT.
Several supermarkets had to discard their chilled and frozen products. Neither ICA nor Coop has explained what caused the failures or whether the affected stores were using the same refrigeration systems.
Similar problems have also been reported elsewhere in Europe. Belgian supermarket operator Delhaize said an IT incident had disrupted some of the refrigeration systems in its stores, NL Times reported .
Belgian media cited by the publication reported that at least 40 Delhaize locations were affected. Carrefour Belgium also said 15 of its stores had experienced problems.
The Swedish and Belgian incidents come just weeks after hackers tampered with refrigeration systems at hundreds of supermarkets in France on 11 October, raising temperatures to around 50°C and forcing stores to throw away food.
There is also a separate investigation in the US, where the Pentagon is looking into whether hackers caused refrigeration failures at military base stores in August.
No connection between the incidents in Sweden, Belgium, France and the US has been established.
Get the most important tech news in your inbox each week.
