The operator of Japan's crippled nuclear power plant says a fresh leak of radioactive water has been discovered.

Tokyo Electric Power Company says about 45 tons of radioactive water has leaked from a purification device at the Fukushima Daiichi plant. Officials say most of the water appears to have remained inside the facility.

TEPCO says about 300 liters of the contaminated water may have leaked into a gutter that leads into the ocean before being blocked with sandbags. Officials say they are checking whether any water reached the ocean.

Japan's Fukushima nuclear power plant was crippled by a massive quake and ensuing tsunami that struck in March. Tens of thousands of people were forced to flee their homes due to leaking radiation.