Japanese prosecutors are not expected to press charges against any state officials or companies over the handling of the 2011 Fukushima nuclear crisis, national media has said.
Sources told the Asahi Shimbun newspaper that despite 15,000 criminal complaints, investigators have found insufficient evidence of responsibility for the 2011 disaster, which developed after a massive earthquake and tsunami,
Prosecutors judged that it would be difficult to prove anyone in charge could have predicted a natural disaster of such proportions. They would also have difficulty establishing a link between the nuclear crisis and casualties among evacuees, the newspaper said.
They have questioned Naoto Kan, prime minister at the time of the disaster, and investigated others including Masataka Shimizu, the president of Fukushima's operator Tepco.
Tepco struggles to contain highly radioactive water that is pouring out from the tsunami-wrecked plant, prompting the government to step in to try to help with the clean-up.
There is still a 20km exclusion zone around the plant, which is leaking radioactive water, but some people who were evacuated are being allowed to return.
In July, increasing amounts of radioactive cesium was detected in groundwater 25 metres from the sea.
A reactor at the Fukushima Dai-ichi power station suffered core meltdowns after the 2011earthquake and tsunami, leading to the world's worst nuclear disaster since Chernobyl in 1986.