About 300 tons of radioactive water leaked from a storage tank at the damaged Fukushima nuclear power plant in Japan, the operator said Tuesday. "We believe the leak has not stopped yet," Yo Koshimizu, a spokesman for Tokyo Electric Power Co said late Tuesday, DPA reported. The operator said it had not identified the exact source of the leak, and that the toxic water had likely flowed into the soil. On Monday, Tokyo Electric said puddles with extremely high radiation levels had been found near the storage tank at its Fukushima Daiichi plant. Radiation levels as high as 100 millisieverts per hour were detected, five times the annual exposure limit for plant workers, according to government guidelines.