Iran has described French accusations that it was behind cyber-attacks that raised the temperatures of supermarket fridges and freezers as "baseless and hostile".
On Monday, the French authorities blamed Iran's Islamic Revolutionary Guard Corps (IRGC) for the string of hacks, which foreign minister Jean-Noël Barrot said were "unprecedented" in terms of their scale and "level of aggression".
He added that those responsible would be hit with sanctions.
The French cyber-attacks, which led to the destruction of tons of frozen and chilled food, were followed by a similar hacks against supermarkets across several other European countries. It is not known if the instances are linked.
Barrot said the attack on France's supermarkets "marks the first large-scale cyber-attack aimed at sabotage on our national territory, and it constitutes a major attack on the nation's interests and the security of the French people".
He said the government had summoned the Iranian ambassador to Paris to "lodge a very strong protest against this extremely grave act".
France will take "any other necessary and proportionate measures" to respond to the incident and "deter anyone who might seek to repeat it", Barrot added.
The Paris prosecutor, Laure Beccuau, said an investigation had been opened into the head of an offensive cyber unit associated with the IRGC as well as his two deputies.
Beccuau named the unit as Shahid Kaveh, which she said had an affiliation with the electronic and cyber centre of the IRGC.
Shahid Kaveh is the name given to a cluster of hackers thought to be directly employed by the Iranian regime.
In recent weeks, a number of commentators and politicians in Iran have argued that the country should extend any retaliation beyond the Middle East if the US and Israel resume the war they started earlier this year.
On Monday, some Iranian media outlets denied the French accusations, but there had been no official comment until Tuesday's statement from Iran's foreign ministry.
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.
Other major food retailers including Carrefour, Monoprix and E.Leclerc were also hit by the attack, which targeted software provided by Danish engineering firm Danfoss.
The software allows retailers to manage their cold units remotely.
Earlier this month a second wave of hacks took place, hitting more than 100 stores across Europe.
Supermarkets in Belgium and Luxembourg were affected, while a smaller number of shops were hit in countries including Sweden, Ireland, the Netherlands, Estonia and Finland.
Separately in August a small number of US military bases had fridges mysteriously malfunction, spoiling food. This incident is also being investigated as deliberate cyber-attacks, Reuters news agency has reported, citing sources familiar with the matter.
Since the waves of attacks on freezers, experts have been speculating which hacking groups could be responsible, with Iran being on a list of potential suspects.
In spite of a pair of Russian-aligned hacktivist groups claiming they were responsible on Wednesday, few believed them.
The French government has not said how it reached the conclusion that Iran was responsible, and attribution of cyber-attacks is extremely hard as hackers are able to hide their locations.
Source: BBC
--Agencies
