There is pressure on Paris to come clean about whether a French-made guided-missile contained a “kill switch” that would have disarmed the Exocet weapon. Three Royal Navy ships were hit by Exocet missiles in the 1982 conflict, with two of the vessels sinking as a result.
Those onboard the HMS Sheffield and Atlantic Conveyor became the first British losses in the war with Argentina.
But claims have now been made that France had the power to stop the attack.
The missiles are thought to have included a back up switch that would allow France to stop itself being targeted by its own weapons should they fall into the hands of a hostile state.
France has always denied such a kill switch existed, but investigations carried out on an earlier variant of the missile have raised doubts.
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Admiral Lord West, the former First Sea Lord who commanded the frigate HMS Ardent during the Falklands war, told The Telegraph: “I was told that the French were very helpful in terms of letting us see the flying of Mirages and the Super Etendard [French-built fighter aircraft, used by Argentina] so we could get their flight profiles.
“They did give us a certain amount of material about Exocet, but I was also told there was a mechanism within it so that foreign people couldn’t fire an Exocet at a French ship without them being able to do something to mean it wouldn’t be able to hit them.
“They were making a lot of sales of Exocet, and if the people they were selling them to found out that there was a way of defeating it, they would not have been happy.”
Tory MPs are now demanding Emmanuel Macron’s government release information about what was known at the time.
Foreign affairs select committee member Bob Seely said: “If Exocets contained what was effectively an on/off switch, the French should have shared that with us.
“If it turns out that information was withheld, that would be one of the most shameful episodes in Anglo-French relations.
“It certainly would have been game-changing had France chosen to share this characteristic of the Exocet.”
A memorial to the 20 soldiers who died on HMS Sheffield is set to be unveiled at the National Memorial Arboretum in Staffordshire on Wednesday to mark the 20th anniversary of the sinking.
However, hopes of pressing France for more information are unlikely to yield results.
Frictions continue to plague relations between London and Paris after a series of rows over Brexit, migrant crossings, and a UK defence pact with the US and Australia.
Mr Macron, who was re-elected as President 10 days ago, is still yet to speak to Prime Minister Boris Johnson via the phone after his victory.
He has spoken to allies such as Germany’s Olaf Scholz and the US’s Joe Biden as well as to other world leaders such as Vladimir Putin.
“We’ll update you in the normal way when they speak,” the Prime Minister’s official spokesman said last night as he looked to downplay concerns of a rift.
“We maintain a strong relationship with France, and that is evidenced by the joint action we are taking against Vladimir Putin in Ukraine.”