PARIS — Cyberattacks disrupted European supermarket chains, affecting refrigeration systems at hundreds of stores in France and forcing a major grocer to shut down websites serving customers in Europe and the United States.

French Finance Minister Roland Lescure told Parliament on Tuesday that about 700 of the country’s 10,000 supermarkets were affected. He said there was no risk to France’s food supplies but acknowledged that the attack “touches the heart of our food security.”

“It was a wake-up call for everyone,” he said.

Separately, Dutch supermarket giant Ahold Delhaize said Tuesday it was working to restore systems it had shut down following what it described as a security issue. The company said its stores — including Albert Heijn in the Netherlands, Delhaize in Belgium and Stop & Shop, Food Lion and Giant in the United States — remained open, but the websites for those brands remained offline Tuesday.

Ahold Delhaize said it had no evidence that customer or employee data had been stolen.

The Paris prosecutor’s office said Tuesday that its cybercrime unit was investigating the large-scale attack in France, including the extent of damage caused by spoiled food and reported fires. According to BFM-TV, hackers forced a continuous defrost cycle and set temperatures as high as 50 degrees Celsius (122 degrees Fahrenheit) on stores' refrigeration systems.

French supermarket group Groupement Mousquetaires, which operates more than 4,000 stores across Europe, said 300 of its Intermarché and Netto stores were impacted. Some refrigerated and frozen food display cases remained out of service Tuesday.

Dominique Schelcher, CEO of French grocery chain Cooperative U, said 80 of the company’s 2,000 stores were affected. Most managed to prevent disruptions to refrigeration, but some had to discard food, he said in a post on X.

“Targeting equipment essential to the preservation of fresh products is an attack on the French food supply chain. It is unprecedented, extremely serious, and unacceptable,” Schelcher said.

Carrefour and Monoprix supermarkets were also impacted.

Suppliers say French systems may have been outdated

The French government’s cybersecurity agency said Tuesday it was “aware of numerous compromises” involving refrigeration system remote control modules made by Danish company Danfoss as well as U.S.-based Copeland.

Danfoss said Monday that most affected systems were older products that no longer received software or security updates, and that it was working with affected customers to limit the damage.

“Danfoss has long advised customers to keep supported systems updated with the latest firmware, as well as to operate behind a firewall,” the company said.

In an August report, U.S. cybersecurity firm Claroty identified vulnerabilities in the Danfoss AK-SM 800A and Copeland XWeb Pro platforms, which are used to manage refrigeration infrastructure in supermarkets, warehouses and other facilities.

For example, Claroty said “numerous controllers” using the Danfoss system were directly accessible from the public internet, leaving them wide open for cyberattacks. But it noted that Danfoss and Copeland had since fixed the vulnerabilities.

Copeland said Tuesday that a vulnerability had been identified in “a discontinued, end-of-life generation of controllers," and that it was working with impacted customers.

Christopher Whyte, an associate professor of homeland security and emergency preparedness at Virginia Commonwealth University, said it’s “not too difficult” to carry out such an attack.

“It looks like almost certainly what happened here was these controls were left open to the broader network being used by the supermarket,” Whyte said.

Similar attacks on water systems, power infrastructure and other kinds of physical operations have been fairly common for years, often coming from Iran and other state actors, Whyte said. Over the summer, Minnesota and Michigan reported cyberattacks on their states’ water systems.

Whyte said attacks on refrigerator systems are not unprecedented. Last month, Stars and Stripes reported that three military agencies were investigating refrigeration outages at U.S. military commissaries that occurred within days of each other. The Associated Press left a message Tuesday seeking comment on that case with the U.S. Army’s Criminal Investigation Division Cyber Field Office.

But Whyte said the scale of the French attack, and the fact that there appeared to be no ransom demand or stealing of information, made this situation unusual.

AI could make cyberattacks more frequent, experts say

It was unclear Tuesday whether the French cyberattack involved artificial intelligence. But advances in AI have contributed to an increase in cybersecurity incidents, said Varun Chandrasekaran, an assistant professor of electrical and computer engineering at the University of Illinois’ Grainger College of Engineering.

Chandrasekaran said there’s also a possibility that the attack happened because of an experiment an AI lab was doing — like what happened with OpenAI's breach of an Australian health department website last month. He said people should absolutely expect an increase in such cyberattacks in the future thanks to AI.

But Chandrasekaran said AI could also be useful in preventing such hacks.

“Right now it seems like a lot of the defensive countermeasures people have are quite passive,” Chandrasekaran said. “What we need is a proactive defender, like another AI model sitting on the defender side that’s trying to counter whatever the attacker AI is doing.”