Tokyo, Nov 7 : Excessive levels of radioactive cesium were detected in mushroom locally grown in Japan's Yamanashi prefecture, a government report revealed on Tuesday. The sample of Cortinarius caperatus, a type of edible mushroom, in the prefecture's Narusawa village, reported a cesium level of 150 becquerels per kilogram (Bq/kg), said the report published by the Ministry of Health, Labor and Welfare on its official website. The allowed cesium level on general food products stands at 100 Bq/kg in the country, reports Xinhua news agency. According to the report, the test was conducted on October 15 and the mushroom was not circulated in the market. The Ministry regularly publishes test results of radioactive substances in foods conducted by a total of 14 prefectural governments in north and east Japan following the accident at the crippled Fukushima No. 1 nuclear power plant. /IANS