An expert opinion in French Polynesia has recommended to throw out 10 of the 12 compensation claims over the French nuclear weapons tests now before the court in Papeete.
Earlier this year, the advice from the court official was to compensate the claimants.
However, changes to a French Finance Act in December reintroduced a minimum figure of radiation exposure, which the expert now said invalidated some claims.
The change in the Act was against the recommendation of a commission set up in 2017 which called for the reference to negligible risk to be removed as a way to improve the 2010 compensation law.
Earlier this year, a French Polynesian member of the French Senate Lana Tetuanui defended the amendment after it caused dismay among test veterans who said the change reneged on the promise to abolish the term negligible risk.
The head of the French compensation commission Alain Christnacht said the change meant that it was brought in line with the Public Health Act.
An opposition Assembly member from French Polynesia, Moetai Brotherson, had earlier raised concern about the amendment.
However, French Polynesia's ruling Tapura Huiraatira party, to whom Mrs Tetuanui belongs, described Mr Brotherson as a frightened virgin because he had been part of her parliamentary advisory group.
France tested 193 nuclear weapons in the South Pacific over a 30-year period, with some of the atmospheric blasts irradiating most islands.