In a nationally televised statement, Prime Minister Naoto Kan said radiation had spread from the four stricken reactors of the Fukushima Dai-ichi nuclear plant along Japan's northeastern coast.
The region was shattered by Friday's 9.0-magnitude earthquake and the ensuing tsunami that is believed to have killed more than 10,000 people, plunged millions into misery and pummeled the world's third-largest economy.
Image: An evacuee is screened for radiation exposure at a testing centre in Koriyama city in Japan on Tuesday, March 15, 2011. (Photographs copyright AP)