FLATWIRE: Sea Radiation from Fukushima Seen Triple Tepco Estimate (Yuko Takeo)

Japan's biggest utility estimated around 4,720 trillion becquerels of cesium-137 and iodine-131 was released into the Pacific Ocean between March 21 and April 30, but researchers at the Japan Atomic Energy Agency (JAEA) put the amount 15,000 trillion becquerels, or terabecquerels.

Government regulations ban shipment of foodstuff containing over 500 becquerels of radioactive material per kg.

Takuya Kobayashi, a researcher at the agency, said on Friday the difference in figures was probably because his team measured airborne radioactive material that fell into the ocean in addition to material from contaminated water that leaked from the plant.

READ MORE: Reuters