Defence Ministry documents, received by a French campaign group, show that in early 1966 the French authorities decided "for political and psychological motives" not to evacuate the Gambier Islands before tests at Mururoa, 500km away.
Within months, this decision proved disastrous.
The papers show that the very first atmospheric blast,
driven by unexpected winds, spewed fallout over the Gambiers, contaminating soil, food and water and exposing the population to levels of radioactivity that, in a single day, exceeded the prevailing recommended dose for a whole year.
This scattered mosaic of documents suggests the authorities did nothing to evacuate, shelter or even advise people of any risk.
The documents suggest other fallout episodes occurred in other tests in the first nine blasts of the atmospheric programme in 1966-67.
France adopted a "safer" technique for detonating bombs until atmospheric tests were replaced by underground ones, from 1974 to 1996.
A French Defence Ministry spokesman confirmed the authenticity of the documents to the Herald but stood by France's position that its tests were safe and that protection measures were rigorously upheld.
Polynesian islanders and test veterans have been fighting a long and mostly fruitless battle to claim compensation from the French Government for ill-health they say was caused by the 30-year nuclear test programme.
But almost all the important documents remain classified, creating a thick defensive wall against compensation demands.
Claimants have always had to take the legal route, arguing on a case-by-case basis.
