As Japan's heroic workers stepped up their critical task of averting a meltdown at the quake-hit Fukushima nuclear facility, Premier Naoto Kan on Friday vowed to win the "long battle" to tackle the crisis at the plant, where high radiation was detected for the first time in groundwater.
Three weeks after the magnitude-9 quake and tsunami struck Japan's northeast where the nuclear plant is situated, thousands of Japanese and US troops launched an intensive three-day air and sea search for thousands of people who still remained unaccounted for following the twin disaster.
Authorities also said that tens of thousands of residents evacuated from areas near the Fukushima nuclear plant may not be allowed home for months, as many of them continued to live in temporary shelters.
In a televised address, Prime Minister Kan said he was ready "to face a long-running battle" at the plant and vowed to win it.
Acknowledging that the nuclear power station, located around 220 km from Tokyo, was not "stable enough yet," Kan promised that he would "inevitably win the battle" and bring the plant under control.
"We cannot say at this stage say by when this will happen, but we are trying our best," he said.
His remarks came as highly radioactive water, which continues to leak from the plant, was found for the first time in groundwater under the crippled plant.
The plant's operator, Tokyo Electric Power Company (TEPCO), said it has been checking underground water on the advice of the Nuclear Safety Commission of Japan.
It said the radioactive water was detected beneath the ground near the turbine buildings of five of the six reactors The remaining reactor, No.4, could not be checked because it was blocked by debris, national broadcaster NHK reported.
TEPCO said that highly radioactive substances dispersed into the atmosphere may have seeped into the soil through rain and sprayed water, three weeks after the mega quake and tsunami damaged the plant and left nearly 30,000 people dead or unaccounted for in the country's northeast .
However, the Nuclear and Industrial Safety Agency said some of the analysis data on the groundwater presented by TEPCO cannot be trusted, casting doubts on findings that the concentration of radioactive iodine in the water was 10,000 times the legal limit.
It said the density readings of radioactive substances in groundwater samples taken on Tuesday and Wednesday from around the No.1 reactor's turbine building may be revised downward, as TEPCO's evaluation programmes for materials such as tellurium, molybdenum and zirconium were found to have errors.
But, it said the firm's analysis programmes for radioactive iodine were confirmed to be correct.