The nuclear accident at Fukushima last year was a "man-made disaster" and not only due to the tsunami, a Japanese parliamentary panel said in its final report on the catastrophe.
"Governments, regulatory authorities and Tokyo Electric Power [TEPCO] lacked a sense of responsibility to protect people's lives and society," the Diet's Fukushima Nuclear Accident Independent Investigation Commission said on Thursday.
"They effectively betrayed the nation's right to be safe from nuclear accidents. Therefore, we conclude that the accident was clearly 'man-made'," it said.
The six-reactor nuclear plant was severley damaged after the March 2011 earthquake and tsunami knocked out cooling systems to reactors, leading to meltdowns and the release of radioactivity.
"According to this commission's study, on March 11, it is believed that the Fukushima Daiichi nuclear power plant was in a vulnerable condition with no guarantee it could withstand earthquakes and tsunamis," the report said.
The government and plant operator TEPCO have been unwilling to say the reactors could have been damaged by the initial earthquake.
An earlier report by TEPCO had all but cleared the huge utility, saying the size of the earthquake and tsunami was beyond all expectations and could not reasonably have been foreseen.
But the report of the commission said: "Despite having a number of opportunities to take measures, regulatory agencies and TEPCO management deliberately postponed decisions, did not take action or took decisions that were convenient for themselves."
It also said that had the company had its way, its staff would have been evacuated from the crippled plant and the catastrophe could have spiralled even further out of control.
The findings call for further investigation into the impact of the 9.0 magnitude earthquake - as opposed to the towering tsunami - on the reactors at Fukushima.
Giant waves crippled cooling equipment at the Fukushima plant, triggering meltdowns that spewed radioactivity and forced tens of thousands of residents to flee.
The commission said in the past that the Japanese government's initial response was slow and inadequate because it was unprepared.
Speaking to Al Jazeera, Imad Khadduri, nuclear scientist and author, said: "These are officials not scientists. They should have assembled a group of scientists and relied on them, but they didn’t. They stayed in their political jacket suits. Yes, there is a shortcoming in that."
"But on the whole, if this kind of calamity has happened in any part of the world, I really doubt that the governments and the scientists in the other part of the world would be able to cope as the Japanese did."
The commission, launched in December at the demand of opposition parties, was designed as an alternative to the administration's investigation into the worst nuclear crisis in a generation.
Kiyoshi Kurokawa, the commission's chairman, said he was confident that the commission had accomplished a "thorough investigation and verification" process during this time.
Kurokawa also said the report includes a new set of policy proposals that should be "steadily implemented step by step with consistent effort to reform".
He stressed that it is the responsibility of Diet members to make sure the recommendations are followed.
The commission said it held over 900 hours of hearings and interviewed more than 1,100 people during the investigation.
Among those interviewed were Japan's former Prime Minister Naoto Kan, former Chief Cabinet Secretary Yukio Edano, as well as key members from TEPCO.