The authorities concerned in Japan said Friday they had found radioactive substances in Japanese green tea,esteemed around the world for its purity and health-enhancing properties, in the nation\'s largest growing region, 370 kilometres south-west of the damaged Fukushima Daiichi nuclear plant. The dried tea leaves from the Warashina area in Shizuoka were found to contain 679 becquerels per kilogram of radioactive caesium, above the officially permitted level of 500 becquerels. But the discovery was made by chance, and the authorities admit that earlier consignments, which were not examined and have gone to the market, may have also been contaminated, reported the Japanese \"Herald Sun\" newspaper today. The Shizuoka government wants the 500 becquerels limit to apply to the less intensely radioactive fresh leaves. But the health ministry argues that consumers might swallow dried leaves in a cup of tea, as well as in products derived from tea, such as green tea ice cream, and that the 500-becquerel limit for fresh vegetables must also apply to tea. Limits on the sale of tea from areas closer to Fukushima have been put in place, but Shizuoka is to green tea what the Champagne region of France is to sparkling wine, and the effect of the news will be devastating. Japan produced 86,000 tonnes of dried tea in 2009, and 42 per cent of that was from Shizuoka. The prefecture, supported by the ministry of agriculture, has insisted on carrying out radiation measurements in such a way as to minimize the suggestion that its precious product is dangerous. Japan produced 83,000 tons of dried tea leaves in 2010, of which Shizuoka prefecture makes up about 40%. The government decided on June 2 to stop shipments of dried tea leaves produced in some areas in the prefectures of Ibaraki, Chiba, Kanagawa and Tochigi after samples of tea leaves in the areas contained more than 500 becquerels of radioactive caesium. Since the plant was hit by the March 11 earthquake and tsunami, it has leaked radioactive substances.