This is double the rate of the rest of the country, where a total of 2,753 cases were diagnosed in the same period. "This is a result which has been checked thoroughly and which is statistically significant," said Dominique Laurier, head of the epidemiology research laboratory at France's nuclear safety research body (IRSN).

The incidence of leukemia is twice as high in children living close to French nuclear power plants as in those living elsewhere in the country, a study by French health and nuclear safety experts has found.

A study on Germany, published in 2007, did find a significantly increased risk, but the COMARE team said these findings were probably influenced by an unexplained leukemia cluster near a nuclear plant in Krummel, north Germany, that lasted from 1990 to 2005.