Earthquakes and tsunami are unavoidable natural events, but the ongoing disaster at the Fukushima No. 1 nuclear plant was induced by "human errors" stemming from cozy ties between bureaucrats and Tokyo Electric Power Co., former Fukushima Gov. Eisaku Sato told The Japan Times on Wednesday.

Sato, who served five terms from 1988 to 2006, said the inappropriate relationship between government bureaus and the utility often resulted in them burying major troubles, including cracks in reactors and safety shortcomings at Tepco's two nuclear plants in the prefecture.

"Their improper bond means that no one was keeping an eye on Tepco," Sato, 71, said, adding it ultimately led to the inadequate preparations for the March 11 disaster.