Britain's defence chief during the Falklands War accused the French of being "duplicitous" after a BBC probe aired on Monday revealed that Paris knew a French technical team was in Argentina during the conflict.

The team, which mainly worked for a company 51 percent owned by the French government, helped Argentina fix faulty missile launchers, group leader Herve Colin admitted in 1982, but French officials interviewed by the BBC denied they were aware of the team's activities.

Former defence secretary John Nott wrote in his memoirs that France was Britain's "greatest ally" during the conflict, but slammed the nation after being presented with new evidence.

"We asked (former French president Francois) Mitterrand not to give assistance to the Argentinians," Nott told the BBC investigation, which was broadcast on Radio 4.

"If you're asking me: 'Are the French duplicitous people?' the answer is: 'Of course they are, and they always have been'," he added.

Some 32 Britons were killed in May 1982 when Exocet missiles were used to strike the HMS Sheffield and Atlantic Conveyor vessels.

Colin admitted in a 1982 interview with The Times that technicians located the faults which were preventing the launchers from firing, adding that "the rest was easy", in apparent contravention of Mitterrand's embargo on French arms sales and assistance to Argentina.

Pierre Lethier, former chief of staff of the DGSE -- France's foreign intelligence agency -- told the BBC that his department knew about the team's presence, but that it was being used to gather intelligence on the Argentinian army.

"This is what intelligence is for, you need sources," he explained. "We had difficulties to penetrate the Argentinian army at that time during the Falklands conflict. So, the more helpers you have the better you are."

Lethier denied that Paris knew of the team's activities, saying that they "bordered on an act of treason, or disobedience to an embargo."

"It's clear that if the head of state in France decrees an embargo, it's an embargo. Full point."

Francois Heisbourg, who at the time was international security adviser to the French Minister of Defence, Charles Hernou, expressed regret over the incident.

"It is now undeniable and... one should not belittle it," he told the BBC.

"This was not what was supposed to be done. It is the sort of thing which mars what should otherwise have been picture-perfect co-operation between the two countries," he added.

Tensions are currently high between Britain and Argentina over the islands, which are controlled by London but still claimed by Buenos Aires, ahead of the anniversary of the invasion by Argentine forces on April 2, 1982.

The ensuing 74-day war cost the lives of 649 Argentine troops, 255 British troops and three Falkland Islanders.