French daily Le Parisien today published military papers that reveal the extent of the radiation risk from Fance's first atomic bomb, nicknamed 'Gerboise Bleue' (Blue Jerboa), which detonated on February 13th, 1960.
The affected zone wasn't restricted, as had been previously believed, to northern, eastern and central Africa but reached as far as the south of Europe.
A map, declassified last year but only published today, showed that by thirteen days after the explosion the radiation had spread to the south-east of Spain, Sicily and Sardinia.
Bruno Barillot, an atomic bomb expert, told Le Parisien that safety regulations in the 1960s "were much less strict than now."
The levels were described by the military as "generally very weak" and of no threat beyond the area of the blasts in the Algerian desert.
But Barillot countered, "That's what the army always say."
Radio-isotopes including iodine 131 and caesium 137 were released but it is impossible to know the exact levels, or by how much they were diluted in the atmosphere.
"No-one today doubts that these elements are causes of cancers and cardiovascular diseases," Barillot said.
"Medical advances have shown that even low doses of radiation can trigger serious diseases ten, twenty or thirty years later."
Although Barillot claimed that the documents had been selectively declassified to obscure the real truth, France's defence department said the process had been carried out by "an independent advisory commission" with no army involvement.
France carried out four atomic bomb tests in the Sahara desert between 1960 and 1961, before Algerian independence, and thirteen more afterwards until finally stopping in 1966.
A French law has recognized some illnesses suffered by French soldiers as being the result of exposure to radiation from the blasts.
But the subject remains a diplomatic thorn in the side of France's relations with Algeria, whose 150,000 citizens living in the blast zone are yet to receive compensation.