An internal probe by Tokyo Electric Power Co. has determined that division chiefs ordered at least three coverups of structural problems at Tepco nuclear plants, company sources said Thursday.

The officials, known as group managers, had instructed workers of General Electric International Inc., which was inspecting Tepco's facilities, to falsify specific inspection reports, according to the firm's findings.

The officials were stationed at Tepco's No. 1 and No. 2 Fukushima plants in Fukushima Prefecture. False reports were also filed for the Kashiwazaki-Kariwa plant in Niigata Prefecture.