Mathieu Tilman, a manager at a Delhaize supermarket in Belgium, said he was shocked by this kind of attack: “I don’t even understand how anyone could do this… How can we end up throwing away so much food? I find it truly distressing. In moments like these, you just feel like quitting your job.”

In Ireland, 13 SuperValu stores were impacted by what the chain’s owner, Musgrave Group, called a cyber-incident. “Replenishment of chilled and frozen ranges in the affected stores is well under way,” a spokesman said on Monday.

A small number of corner shops in the Netherlands also suffered disruption. Last month, supermarket chain Albert Heijn had to take several services offline because of a separate cyber-attack.

In Portugal, the Mosqueteiros group said that incidents at seven Intermarché stores had been linked to a cyberattack, which “appears to have targeted an external service provider responsible for managing the refrigeration systems”.

Swedish chain ICA also said “a limited number” of its stores had experienced refrigeration problems, without confirming a cyber-attack, and Sweden’s national cyber-security agencies said they were monitoring the incident.

In Finland, irregular temperatures were detected in a few smaller grocery stores belonging to the Kesko group, which said it was investigating the issue.

In Estonia, at least one supermarket was attacked by hackers who raised the temperature in the refrigeration units to 50C, public broadcaster ERR reported.