France's national blood service has said hackers accessed control systems and boosted temperatures at three cold stores stocking vital blood products, in an apparent escalation of recent cyber-attacks on fridges and freezers across Europe. This was reported by Qazaqyia.kz citing The Guardian.

The French blood service (EFS) said temperature and defrosting thresholds had been raised to "very high levels" in the attack, adding that its alarm systems had allowed technicians to intervene before the products were compromised.

The EFS is France's public blood transfusion operator, collecting, testing, preparing and distributing products such as blood, plasma and platelets to more than 1,900 hospitals around the country. It supports more than a million patients a year.

The attack, which EFS said had occurred overnight on Monday, came as the temperatures of refrigerators and freezers in supermarkets in almost a dozen European countries soared as high as 50C (122F), causing millions of euros of food damage.

Retailers in Italy, Germany, Romania and the UK were targeted on Tuesday, after Belgium, Estonia, Ireland, Finland, Luxembourg, the Netherlands and Sweden reported problems with their refrigeration systems the previous day.

In a wave of attacks in France last month, hackers seized control of cooling units in as many as 700 supermarkets. A regional branch of France's Crédit Mutuel bank said on Wednesday it had been the victim of a cyber-attack.

Something similar may have happened in the US in early August, when a series of mysterious fridge malfunctions hit commissaries in at least six military bases. The Pentagon is investigating a suspected hack.

After Italy's government held emergency talks with intelligence officials on Tuesday, Thomas Regnier, an EU spokesperson, said the bloc's agencies were holding urgent discussions with national authorities to formulate a collective response.

"These are not isolated incidents and of course we have to be collectively resilient and prepared for such cyber incidents," he said, declining to name any potential culprits. No motive for the attacks is known and no one has claimed responsibility.

A growing range of devices, including commercial refrigeration systems, can be monitored and controlled remotely. Without patching to repair emerging vulnerabilities, internet-connected software can leave code open to hackers.

Some authorities and experts fear government-sponsored hybrid attacks in the aftermath of Russia's 2022 invasion of Ukraine. Western intelligence officials say Moscow is waging a campaign of sabotage in Europe that is taking many forms.

Rafe Pilling, the senior director for threat intelligence at the cybersecurity company Sophos, told the Guardian this week the most plausible attribution scenarios were a "state-based signalling and demonstration of capability" or a lone-wolf hacker.

EFS said it was not directly targeted, with the attacks hitting cold stores run by its contractors. Products stored in the affected rooms, which included plasma bags for transfusions and medicine manufacturing, had been moved to other sites.

It added that France's national cybersecurity agency (ANSSI) and the health ministry had been alerted, and monitoring of all its equipment had been reinforced.