Three workers have been exposed to radioactive elements and injured at Japan's tsunami-crippled plant.
Fumio Matsuda, a spokesman for the country's nuclear safety agency, said the workers were laying electrical cables at the Fukushima Dai-chi plant at the time.
He said two of the workers were exposed to radioactive elements on the skin of their feet while working on the cables at Unit 3 of the Fukushima facility, and were taken to hospital for treatment.
They were exposed to radiation levels of up to 180 millisieverts, which is less than the maximum 250 millisieverts that the government is allowing for workers at the plant.
The latest troubles at the nuclear plant came as shops across Tokyo began rationing goods including milk, rice and water as a run on bottled water coupled with delivery disruptions left shelves bare, nearly two weeks after the earthquake and tsunami.
Government spokesman Yukio Edano pleaded for calm, and officials urged residents to avoid panicked stockpiling, sending workers to distribute three small bottles of water each to an estimated 80,000 families with babies of 12 months or younger.
Anxiety over food and water remains high a day after Tokyo officials reported radioactive iodine in the city's tap water measured more than twice the level considered safe for babies.
New readings now show the capital's tap water is back to safe levels, but the relief was tempered by elevated levels of the cancer-causing element in two neighbouring prefectures, Chiba and Saitama.
Radiation has been leaking from Fukushima, 140 miles north east of Tokyo, since it was struck by the March 11 quake and engulfed by the ensuing tsunami. Feverish efforts to get the plant's crucial cooling system operating have been beset by explosions, fire and radiation scares.
More than two dozen people have now been injured trying to bring the Fukushima Dai-ichi plant under control.