For 50 years, residents of the French village of Pont-Saint-Esprit have tried to understand the "cursed bread" incident, a moment of terrifying mass insanity and hallucinations that left at least five dead and dozens in asylums. Now the mystery is solved: the CIA secretly spiked the bread from the bakery with enormous quantities of LSD as part of its cold war mind-control experiments, at least according to recently uncovered documents. The allegation originates with H P Albarelli Jr., an investigative journalist who uncovered the documents while researching his forthcoming book, A Terrible Mistake: The Murder of Frank Olson and the CIA's Secret Cold War Experiments.

One man tried to drown himself, screaming that his belly was being eaten by snakes. An 11-year-old tried to strangle his grandmother. Another man shouted: "I am a plane", before jumping out of a second-floor window, breaking his legs. He then got up and carried on for 50 yards. Another saw his heart escaping through his feet and begged a doctor to put it back. Many were taken to the local asylum in strait jackets…

Scientists at Fort Detrick told him that agents had sprayed LSD into the air and also contaminated "local foot products".

Mr Albarelli said the real "smoking gun" was a White House document sent to members of the Rockefeller Commission formed in 1975 to investigate CIA abuses. It contained the names of a number of French nationals who had been secretly employed by the CIA and made direct reference to the "Pont St. Esprit incident." In its quest to research LSD as an offensive weapon, Mr Albarelli claims, the US army also drugged over 5,700 unwitting American servicemen between 1953 and 1965.