France summoned Iran's ambassador on Tuesday after accusing Tehran of a cyberattack that disabled refrigeration systems in hundreds of French supermarkets last month.

Foreign Minister Jean-Noël Barrot said Paris would push for European Union sanctions in response to what he called an attack of “unprecedented scale and aggression” against France. Speaking on France Info television, he warned that France could respond with cyber measures of its own and would not rule anything out.

“We will take whatever measures are necessary, including some that we will not discuss publicly, if we judge them proportionate and necessary to deter any new attacks and punish those responsible,” Barrot said, according to Reuters.

What happened in October

French officials said on Monday that Iran's Revolutionary Guards were behind the attacks, which struck commercial refrigeration systems across France on 11 and 12 October. Hackers took control of controllers supplied by Danish firm Danfoss and Italy's Dixell, pushing temperatures in fridges and freezers as high as 50C and spoiling large quantities of food.

About 700 of France's 10,000 supermarkets were affected, and food worth tens of millions of euros was lost, according to reports. Paris prosecutor Laure Beccuau said investigators had evidence linking the attack to Shahid Kaveh, a cyber unit affiliated with the Revolutionary Guards, and a formal judicial investigation has been opened into its head and two deputies.

The French foreign ministry said the ambassador was received by the ministry's secretary-general on Tuesday morning so France could express its “firmest condemnation” of the attacks. Iran's mission to the United Nations did not return messages seeking comment on Monday.

EU sanctions push

Barrot said France would seek sanctions “at a European level” against everyone responsible for the attack. Kaja Kallas, the EU's chief diplomat, said the bloc's response “should be strong”, and EU foreign ministers are due to discuss the matter at their council meeting next Monday.

The attacks were among the most disruptive cyber incidents since the Iran war began in February, a conflict marked by sporadic episodes of suspected digital sabotage. France's cyber crisis co-ordination centre described the October attack as unprecedented in its scale and level of aggressiveness.

EU food and agriculture commissioner Christophe Hansen said the attacks were “a deliberate attempt to disrupt our food supply chain and undermine consumers' confidence in it”.

The supermarket groups hit included E-Leclerc, Intermarché, Carrefour, Monoprix and Cooperative U. In some stores the overheating equipment caused fires, and spoiled food had to be discarded in large quantities. The attacks also affected refrigeration beyond supermarkets, with blood bank freezers and sites elsewhere in Europe reported hit.

Barrot first made the accusation on Monday on the sidelines of the G7 foreign ministers' meeting in Paris, where he told reporters he could confirm that the Revolutionary Guards were responsible. The Paris prosecutor's office said it had requested international arrest warrants for the head of Shahid Kaveh and his two deputies.

France's national cybersecurity agency, ANSSI, attributed the attack to the Shahid Kaveh group, which it described as a cyber unit affiliated with the Revolutionary Guards.