The magazine said there were "several kilograms" of the substance in the sediment of the lagoons at the Muroroa and Fangataufa atoll sites, where France carried out 193 atmospheric and underground nuclear blasts between 1966 and 1996.
Quoting a scientific report to the International Atomic Energy Agency, the magazine says plutonium particles have been scattered over the surface of three islands near the main test site on Muroroa.
"The study says radioactive tritium is leaking into the lagoons (of the two atolls) from cavities left by underground tests, creating concentrations often 10 times higher than in the open ocean," said the Dominion newspaper in Wellington, New Zealand.
The study, by independent scientists, was to verify monitoring by the French government. It also finds that the lingering nuclear contamination from the tests was unlikely to harm the nearest residents, some 80 miles (130 km) away, or damage the natural environment.
New Zealand has consistently questioned French assurances that the South Pacific nuclear testing programme would cause no environmental or human harm.
A spokeswoman for New Zealand foreign minister Don McKinnon confirmed the government had received a copy of the report and would study it but would not comment before doing so. "It is an independent scientific report," the spokeswoman said. "Now it is open to scientific review and scrutiny."
The report is expected to be tabled at an International Atomic Energy Agency conference in Vienna next week.Reuse content