The seabed samples collected 3km from Minamisoma and another 3km from Naraha, both in Fukushima Prefecture, contained 98 to 190 becquerels of radioactive iodine per kg and 1,200 to 1,400 becquerels of radioactive cesium.
The normal readings for the materials can be up to several becquerels, the utility said.
TEPCO said that it believes the radioactive substances may have fallen into the sea after being released into the air from the plant or may have been carried by contaminated water that seeped from the plant. (ANI)