The testimony of Oscar Carrizo, 33, who commanded a mortar group, brings a new dimension to Scotland Yard inquiries into alleged British war crimes during the conflict. Detectives are expected to visit Buenos Airies within the next two months.
Mr Carrizo, who is married, with three children, now works as a guard with a security firm in Buenos Aires. He described in graphic detail the events of 12 June 1982, which left him blind in one eye.
British forces had captured Mount Longdon after one of the bloodiest battles of the Falklands war. Though the close combat was over, the mountain was still under long-range bombardment and sniper fire. Mr Carrizo, then Corporal Carrizo, said that he was hiding from a passing British patrol when he felt a tap on his helmet. Turning round, he saw two British paratroopers behind and above him.
'I stood up with my gun,' he said. 'They made signs about my gun. I handed it over and they threw it down. Then they signalled about the ammunition belt, which I handed over, then my jacket - everything. They were talking among themselves. It happened very quickly. One of them, the one with the narrow eyes, said to me, in his language, 'American. Green beret.' I have no idea what he meant. Then one of them fired and I felt nothing else.'
Shot through the head, he does not know how long he was unconscious. 'When I got up I was dizzy and sick. But I just felt a bit uncomfortable in my head.
'I took off my helmet and I saw the exit hole, like a little flower. I touched my head and felt something hard and then something soft that the doctor later told me was brain. My hand moved down on to my face where I felt some blood and I came across my eye, hanging down my face. I put it back where it belonged.'
Senior Argentine officers have said that they were not aware of any such executions during the Falklands war and have cast doubt on the allegations of British war crimes, first made by a former British paratrooper in 1991. But Mr Carrizo's account is supported by Santiago Mambrin, also a veteran of the battle for Mount Longdon, who has said that he witnessed the 'execution' while hiding 30 metres away.
Mr Carrizo was later picked up by British medics and treated on board a British hospital ship before being returned to Argentina. He survived his injuries, although he lost the use of his left eye.
Argentina's deputy foreign minister, Fernando Petrella, told the Independent that British detectives are expected to fly to Argentina 'within the next two months' to pursue their war crimes inquiry. Mr Petrella said that the Argentine government was notified at the end of last year that detectives wished to come to Argentina and had received a list of names of the people Scotland Yard wants to interview. 'The government of Argentina has said that it will co-operate with the British inquiry,' Mr Petrella said.
The investigation, led by Detective Superintendent Alec Edwards, of the International and Organised Crimes Squad, was taken over by Scotland Yard from the military police last year. It began after Vincent Bramley, a former officer of the 3rd Battalion, the Parachute Regiment, alleged in his book Excursion to Hell that fellow paratroopers had executed Argentine prisoners after the battle for Mount Longdon.
Although Scotland Yard detectives have visited the Falkland Islands twice they have not yet questioned Argentine veterans. Earlier this month, on Scotland Yard's second visit to the Falklands, the police carried out excavations on Mount Longdon, with assistance from a former British soldier who served in the war.
The Argentine and British governments now enjoy good relations and the Argentine President, Carlos Menem, hopes to visit Britain this year. Both governments recognise that such serious allegations must be investigated, but both regard the Scotland Yard inquiry as a potentially explosive and damaging issue.