TOKYO, Nov. 28 (Kyodo) — Tokyo Electric Power Co. said Monday that the head of its troubled Fukushima Daiichi nuclear power plant has been hospitalized and will be relieved of his post for medical treatment, effective Thursday.

The utility declined to provide details regarding 56-year-old Masao Yoshida's illness and his accumulated radiation exposure, citing privacy, only saying that doctors have not indicated a link to radiation. His illness was detected during a recent checkup, TEPCO said.

Yoshida has been directing onsite operations to bring the radiation-leaking plant under control since the March 11 earthquake and tsunami triggered Japan's worst nuclear crisis there. He will be succeeded by Takeshi Takahashi, 54, head of the nuclear power and plant siting division.

"Upon the doctor's judgment, it has become inevitable for me to be hospitalized for treatment," Yoshida said in a message to the plant's workers, according to TEPCO. "It breaks my heart to have to bid farewell in this way to you all, with whom I have worked since the disaster."

Regarding the change in personnel, Chief Cabinet Secretary Osamu Fujimura told a regular news conference that the government will keep a close watch on developments to ensure ongoing efforts to bring the crisis under control are not affected.

Yoshida, who became the plant's chief in June 2010, drew media attention over his decision to continue injecting seawater into one of the troubled reactors at the Fukushima Daiichi complex as an emergency step in the early days of the crisis, despite the utility's decision to suspend seawater injection.

He revealed the truth two months later and was reprimanded by TEPCO, although his decision was widely seen by experts as technically appropriate for cooling down the nuclear fuel in the reactor.

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