More than six times the legal limit of radioactive caesium has been found in beef from Fukushima prefecture, home to Japan's crippled nuclear plant.
A Tokyo official says the meat was taken from one of 11 cows shipped to Tokyo from a farmer in Minamisoma city.
The 11 cows all showed high levels of radioactive caesium, ranging from 1530 to 3200 becquerels per kilogram, compared with the legal limit of 500 becquerels.
It is the first time excessive levels of radioactive caesium have been found in meat, the AFP reports.
The city of Minamisoma lies on the outskirts of the Fukushima Daiichi nuclear power plant, which has leaked radioactive substances into the environment after the 11 March tsunami and earthquake crippled its cooling systems.