Japan's Kyodo News reported on Tuesday that high levels of radioactive substances were detected in a drainage system 100 kilometers away from the Fukushima Daiichi nuclear power plant.
The excessive levels of cesium were found in a ditch at the Fukushima district court in Aizuwakamatsu City.
When tested the radiation from the sludge from the drainage system amounted to 186,000 becquerels per kilogram.
This news of the spread of radiation comes as researchers at the University of San Diego in California said they detected twice the number of radioactive particles in their air filters from Japan's nuclear accident in March.