French Polynesia's nuclear test veterans say they fear the former test sites at Moruroa and Fangataufa will remain closed to independent inspectors.
Last week, the French Senate approved a bill to return the two atolls to French Polynesia by 2014 but the National Assembly is widely expected to vote against it.
France promised to return the atolls after the weapons tests ended but Paris now invokes confidential defence issues to block access.
The head of the Moruroa e tatou veterans group, Roland Oldham, says there is concern that Moruroa poses serious risks and wants to have the site inspected by others than the French military.
"If there is a collapse, what's going to happen to the leaking of radioactivity and the many kilos of plutonium inside of Moruroa?"
The head of Moruroa e tatou veterans group, Roland Oldham