A worker battling to cool overheating reactors at Japan's tsunami-hit nuclear plant was taken to hospital on Sunday after complaining of feeling sick, the plant's operator said.
The man had no apparent injuries and it was not clear what had caused the sudden illness, said a spokesman for Tokyo Electric Power (TEPCO), which runs the stricken Fukushima No. 1 plant.
"A subcontractor, a man in his 30s, complained that he was feeling unwell at around 11:10," said the spokesman. "He was conscious but somewhat wobbly. He could walk if assisted.
"He was transferred to a hospital. The cause of his sickness is not yet known."
The spokesman said the worker, who has not been identified, was one of 30 who had been laying a water exhaust hose outside the turbine building at reactor No. 2.
Increasing amounts of highly radioactive water have been gathering in a trench at the reactor, where workers successfully plugged a leak that had been spewing badly contaminated water into the Pacific Ocean.
The company has dumped more than 10,000 tonnes of low-level contaminated water into the sea to free up storage space so they can begin draining the trench.
Last month three workers working on the turbine in reactor No. 3 were hospitalised after standing in highly radioactive water.
They were discharged a short time later, despite having been exposed to an estimated 2,000 to 6,000 millisieverts of radiation on their feet.
Normally about half of people who receive a 5,000 millisieverts dose across the entire body would be expected to die within a month.