There has been a strong reaction by a French scientist to claims that last month's publication of his findings was a media stunt.
The head of the INSERM institute, Florent de Vathaire, established a link between French nuclear weapons tests in the South Pacific and the incidence of thyroid cancer among women exposed to test fallout.
This was made public in a letter released by the French Polynesian president, Oscar Temaru.
But a new test veterans' organisation formed this year, Tamaraii Moruroa, says the letter amounts to a call on politicians to give more funding and not proof of a cancer link.
Mr de Vathaire has now accused the organisation of deliberate defamation, saying it uses slanted comments and lies.
He has told the Tahitipresse news agency that he is the victim of political manipulation.
Tamaraii Moruroa was formed less than six months ago and calls itself an apolitical organisation.
The French state recognises no causal link of its atomic tests and poor health, while the US has acknowledged links between its weapons tests and some cancers.