Officials in Japan were "astonishingly unprepared" for the events that led to the Fukushima nuclear disaster, a damning report has concluded.
Investigators highlighted a catalogue of human errors before and after the earthquake and tsunami which killed thousands of people, devastated the Japanese economy and threatened the future of the nuclear industry.
The independent report, published in the Bulletin of the Atomic Scientists, criticised the building of multiple nuclear reactor units so close together, and the failure to take the risk of a deadly tsunami seriously.
The nine-magnitude earthquake on March 11 last year triggered a 14-metre tsunami which wiped out coastal towns, shut roads, severed communications and claimed thousands of lives. It also cut off all electricity to the Fukushima Daiichi nuclear power station, setting the stage for a major nuclear accident.
After the disaster the Rebuild Japan Initiative Foundation set up an independent panel to review the actions and responses of the Japanese government, nuclear plant owners the Tokyo Electric Power Company (Tepco) and regulatory agencies.
The report, written by foundation chairman Yoichi Funabashi and investigation panel director Kay Kitazawa, said the tsunami could and should have been anticipated.
Tepco was said to bear the primary responsibility for incompetent handling of the disaster's aftermath. The organisation failed to make rapid decisions and lost the government's trust, it was claimed.
Japanese government regulators including the Nuclear and Industrial Safety Agency and the Nuclear Safety Commission were criticised for their lack of leadership.
The authors concluded: "It's clear from our investigation of the Fukushima Daiichi accident that even in the technologically advanced country of Japan, the government and the plant operator, Tokyo Electric Power Company, were astonishingly unprepared, at almost all levels, for the complex nuclear disaster that started with an earthquake and a tsunami. And this grave oversight will affect the Japanese people for decades.
"Ultimately, the final outcome of studies of Fukushima Daiichi should be an intense effort to build up the resilience of the country, its organisations and its people, so future disaster can be averted or responded to effectively."