France has accused Iran of being behind cyber-attacks that raised the temperatures of supermarket fridges and freezers.

Speaking at a news conference, French Foreign Minister Jean-Noël Barrot said the attack was carried out by the Islamic Revolutionary Guard Corps (IRGC) of Iran.

He said the attack was "unprecedented in both its scale and its level of aggression", adding that the country would "implement sanctions at the European level against all those responsible for this attack."

The cyber-attack last month saw fridges and freezers in hundreds of supermarkets across France heated up, which spoilt fresh and frozen food estimated to be worth millions of euros.

Then last week, dozens of supermarkets across seven other European countries were also impacted by a cyber-attack that targeted fridges and freezers. It is not known if the instances are linked.

Iran is yet to respond to Barrot's allegations.

Separately on Monday, the Paris prosecutor said an investigation had been opened into the head of an offensive cyber unit associated with Iran's Islamic Revolutionary Guard Corps (IRGC) as well as his two deputies.

Laure Beccuau named the unit as Shahid Kaveh, which she said had an affiliation with the electronic and cyber centre of the IRGC.

On 11 October, hackers gained control of the software that regulates the temperatures of the refrigeration units used in many of France's supermarkets.

More than 100 of Coopérative U's supermarkets were hit, as well as 180 stores from Intermarché and its Netto brand. In some stores, temperatures of the fridges reportedly rose to 50C (120F) overnight.