PARIS - An official French investigation has acknowledged for the first time that fallout from atmospheric nuclear blasts accidentally landed on islands in French Polynesia and calls for doctors to closely monitor the health of some 2000 people.

The overall population of French Polynesia received only a low dose of radiation from this fallout but some people were exposed to relatively higher levels, the report says.

It calls for a far-ranging study into the health of around 2000 people who live within a 500km radius of the former test sites, and recommends that these people be given regular checkups in the future.

The document was written by top French nuclear safety official Marcel Jurien de Graviere and presented in Tahiti and Paris this week.

It is the findings of a probe into the 41 atmospheric tests that were carried out at Mururoa and Fangataufa atolls over eight years. From 1975, all subsequent nuclear blasts were carried out underground and the programme was stopped in 1996.

"The fallout from the atmospheric tests conducted by France between 1966 and 1974 involved all of Polynesia at levels that most often were very low. However, the fallout from certain tests affected some islands and atolls more significantly because shifting winds caused the [fallout] cloud to deviate from the forecast path," says the report.

Wind shift of this kind occurred in 10 tests, six of which led to fallout landing on inhabited areas. Fallout comprises water droplets, dust and other debris from the blast that are contaminated by radioactive elements.

The first was a 30-kilotonne blast, codenamed Aldebaran, on July 2, 1966, which affected the island of Mangareva, the main island of the Gambier group. Other ill-starred tests affected the Gambier archipelago on September 24 1966 and again on August 8 1971; Tureia, on July 2 1967 and again on June 12 1971; and Tahiti, on July 17, 1974.

Jurien de la Graviere is in charge of French nuclear military safety. He was asked by the French defence ministry to write the report in order to address accusations of a coverup about the test programme. Associations for military veterans and Polynesians who worked on the test sites say cancer rates among their members run at almost twice that of the general population and are demanding compensation and sickness pensions.

The new report was compiled in a year-long examination of secret files, looking in particular at radiological measurements that were taken across Polynesia at each test - Geiger-counter recordings of radioactivity levels of plants, animals, food, water and the air.

Using this data, de la Graviere made estimates of the likely level of radioactivity, expressed in millisieverts (mSv) to which the populace would have been exposed through breathing, eating and drinking.

"Almost none of the Polynesian population received general doses which were more than 5mSv or thyroid doses that were above 50mSv," says the report. However, some children aged between one and two in Mangareva and in Gambier may have received estimated thyroid doses of 80 and 98mSv in the Aldebaran test in 1966 and in a test codenamed Phoebe in 1971, it says.

To give a comparison, under France's current safety regulations, 100mSv is the threshold which requires the authorities to distribute iodine tablets to exposed populations after a nuclear accident. The International Commission for Radiological Protection recommends maximum exposure of 1mSv per year in addition to background radiation from natural sources and X-rays for medical reasons.

Opponents of the nuclear tests say the report indirectly backs their contention that the whole truth is yet to be uncovered.