French Polynesia's nuclear test veterans organisation Moruroa e tatou says it's concerned of possible contamination because part of the test atoll is sinking.
Its head, Roland Oldham, says a section of Moruroa, which was the main French weapons test site in the Pacific for 30 years, has subsided.
Mr Oldham says he fears that radioactive waste is seeping into the sea.
"The problem today is because one part of the island is going down, all this is under water and the water is one of the worst enemies of stocking all these dangerous things."
Roland Oldham
