The All Japan newsese government confirmed that it has no written records of official meetings held in the aftermath of the nuclear accident which occurred at Fukushima last March.
Written records are a key information for investigative teams trying to establish causes of disasters.
Yukio Edano, currently Trade Minister and spokesman at the time of the crisis, apologized on Tuesday for failing to document the discussions, while another official, Deputy PM Katsuya Okada, confirmed on Friday that other four emergency committees failed to keep records of the meetings.
Okada asked ministers to restore the content of the discussions retroactively, by the end of the next month, an unnamed official said.
According to estimations of the authorities, clearing up the circumstances of the nuclear accident may take up to 40 years.