A suspected cyberattack on supermarket cooling systems spread across Europe on Monday, disrupting refrigeration at stores in six countries and forcing retailers from Sweden to Ireland to throw away spoiled food.

This article has been updated throughout as the story developed.

Sweden's National Cyber Security Centre is handling several cases involving disruptions to supermarket cooling systems, its head, John Billow, told Reuters.

In Belgium, refrigeration company Sabcobel confirmed that a cyberattack was responsible for the disruption. Its chief executive, Stephan Moelans, told Belga that the units' evaporators had been switched into defrost mode.

Many will require physical modifications to restore them, AFP reported, and no one has claimed responsibility for the attacks.

The first reports emerged in Sweden overnight into Monday. ICA Kvantum in Sjöbo said on Facebook that hackers had accessed its cooling systems and set its refrigerators and freezers to 50°C. The store closed for the morning, according to Swedish public broadcaster SVT.

At an ICA Nära store in Böda, on the island of Öland, the manager arrived to find water covering the floor and a freezer displaying a temperature of 55°C, SVT reported. Several stores were forced to discard chilled and frozen products.

ICA confirmed that a limited number of stores had been affected, telling the BBC that all of them operate outside its central network. Coop initially reported problems at six stores, later raising the number to seven out of its 800 locations in Sweden. The retailer said the situation was under control.

Belgium reported a wider disruption. Delhaize said an IT incident had affected refrigeration at its stores, with Belgian media reporting that at least 40 locations were involved, according to NL Times.

Refrigerators at some Delhaize stores reached 15°C, broadcaster VRT reported. Carrefour Belgium reported problems at 15 stores, while around five Spar locations were also affected.

As the day progressed, reports emerged from more countries. Ahold Delhaize said stores in Luxembourg had been affected, Reuters reported.

In Ireland, 13 SuperValu stores reported problems. Retailers in Finland and Estonia also experienced disruptions, although the affected chains were not identified.

The incidents follow a similar attack in France on 11 October, when hackers tampered with refrigeration systems at hundreds of supermarkets, pushing temperatures to around 50°C. In the US, the Pentagon is investigating freezer failures at stores on military bases in August.

So far, there is no evidence linking the incidents in Sweden, Belgium, France and the US. Neither ICA nor Coop has said whether the affected stores use the same refrigeration systems.