Chains in seven countries say cooling unit temperatures rose overnight in incident similar to hack of French shops

Supermarket chains in at least seven European countries have said the temperatures of refrigerators and freezers in some of their shops soared overnight to as high as 50C (122F), echoing a cyber-attack last month that caused millions of euros of damage in France.

Retailers in Belgium, Estonia, Ireland, Finland, Luxembourg, the Netherlands and Sweden reported problems with their refrigeration systems on Monday, and several companies confirmed they had been hacked.