TEPCO president Masataka Shimizu "fell sick last night and has been hospitalised," said a TEPCO spokesman, without elaborating further on his physical condition.

Shimizu, 66, was suffering from high blood pressure and dizziness, public broadcaster NHK said. He had been due to give a press conference Wednesday, which would have been his first public appearance since March 13.

TEPCO has come under fire for its handling of the world's biggest atomic accident since Chernobyl in 1986.

A massive earthquake and tsunami knocked out the cooling systems of the plant's six reactors -- triggering explosions and fires, releasing radiation and sparking global fears of a widening disaster.

Investors have dumped the stock amid signs the company is likely to face a hefty compensation bill and on speculation it may be nationalised amid slow progress in stabilising the plant.

TEPCO shares have lost three quarters of their pre-earthquake value, having plunged to their lowest level in 47 years.

The company said chairman Tsunehisa Katsumata will speak to the press on Wednesday instead of Shimizu.

On Monday TEPCO said Shimizu fell sick during the crisis and took several days off from the joint task force that had been set up by the government and the company.

The Mainichi daily had quoted a senior TEPCO official as saying Shimizu had been so sick that he had stayed "mostly in bed" in a separate room in the building where the task force was meeting.

Shimizu has not appeared in public since attending a press conference on March 13, leading to criticism from local media.