apanese prosecutors have stuck to their decision not to indict three former Tokyo Electric Power Co (Tepco) executives over their handling of the 2011 Fukushima disaster, but a rarely used citizen's panel could still force an indictment.

The prosecutors decided not to issue indictments because of insufficient evidence, a spokesman for Tokyo District Public Prosecutor's Office said on Thursday.

Prosecutors declined in 2013 to charge more than 30 Tepco and government officials who had been accused by residents of ignoring the risks of natural disasters and failing to respond appropriately to the nuclear crisis.

The Tokyo District Prosecutors Office reopened the case after a citizens' panel ruled in July that the three former Tepco executives, including former Chairman Tsunehisa Katsumata, should be indicted over their handling of the world's worst nuclear disaster since Chernobyl in 1986.

The panel had ruled that Katsumata, along with former Executive Vice-Presidents Sakae Muto and Ichiro Takekuro, had failed to protect the Fukushima Daiichi nuclear plant despite warnings of the dangers it faced from big tsunamis.

The 11 unidentified citizens on the panel, the Prosecutorial Review Commission, can still force an indictment by court-appointed lawyers if eight members of the panel now vote in favor.

The Commissions, made up of citizen selected by lottery, are a rarely used but high-profile feature of Japan's legal system introduced after World War Two to curb bureaucratic overreach.