The head of the Fukushima No. 1 nuclear power plant, who will be relieved of his post effective Thursday for medical treatment, told workers to disregard Tepco's order to stop injecting seawater into a reactor soon after the crisis erupted in March, according to government and other sources.

Masao Yoshida, who has drawn media attention for continuing the seawater injection despite Tokyo Electric Power Co.'s decision to suspend the measure, told workers not to obey his ensuing instruction before going on to order them to stop injecting the water, government and Tepco sources said.

While some people have criticized Yoshida's unilateral action, others have said he kept the crisis from growing even worse as workers scrambled to try to get the plant back under control.