Tokyo/Fukushima: Three workers were exposed to high radiation at Japan's troubled Fukushima nuclear plant on Thursday.

Three workers were exposed to high radiation at Japan's troubled Fukushima nuclear plant on Thursday, as authorities mulled plans to import bottled water amid a panicked rush to buy it after the tap water here was briefly declared unfit for infants due to contamination.

More countries, including Russia, Australia and Canada, shunned food imports from Japan. The three affected workers at the crippled Fukushima plant, 220 kms from Tokyo, were laying cable at the No.3 reactor's turbine building when they were exposed to high radiation. Two of them were hospitalised due to injuries to their legs.

They were exposed to 170-180 millisievert of radiation, the Nuclear and Industrial Safety Agency said, adding that two of the workers had their feet under water while laying the cable, an agency reported.

The radiation exposure level was lower than the maximum limit of 250 millisievert set by the Health Ministry for workers tackling the crisis at the Fukushima plant.

Authorities detected radiation levels considered to be unsafe for infants to drink at several purification plants outside Tokyo, local officials said, a day after the tap water in Japanese capital was declared unsafe for babies due to radioactive iodine.

However, Tokyo officials' latest survey showed that the radiation levels dropped to 79 becquerels from 210 becequerels at a purification plant in Kanamachi district, prompting them to say that they would no longer warn against consumption of tap water in the metropolitan area.

Japanese authorities also stepped up their efforts to increase the supply of bottled water in light of the drawn-out crisis at the quake-hit nuclear power plant, as stores in Tokyo were running out of the commodity.

Chiba Prefectural officials said they detected traces of radioactive iodine at about twice the stipulated safe limit for infants in water taken from two purification plants in Matsudo on Wednesday.

Local officials there recommended residents not give tap water to infants as levels of iodine-131 rose to 220 becquerels per one litre of water at one of its purification plants and 180 becquerels at another facility.

The city of Kawaguchi in Saitama Prefecture said the iodine level rose to 120 becquerels per litre of water at its treatment facility on Tuesday, adding that the levels on Thursday have stayed below the limit of 100 becquerels for infants. However, Kawaguchi officials said tap water in the city is safe enough and they would not issue a warning on its consumption.