Tokyo Electric Power Co.'s draft investigation report on the Fukushima No. 1 nuclear plant disaster states that "unnecessary confusion" was fueled by interference from people at the prime minister's office, sources said.

Because people at the office directly tried to question plant chief Masao Yoshida after the crisis started March 11, 2011, Yoshida had to divert his attention from dealing with the rapidly worsening disaster and respond to the office, the sources said.

Such behavior "just put the plant chief in a dilemma and did not improve the outcome of efforts to address the accident," the sources quoted the draft as saying.