Pressure is mounting on Japan to expand the evacuation zone around the Fukushima Daiichi power plant, as the prime minister says he plans to review the country's nuclear energy policy.
The government has so far resisted calls to evacuate more people from the area, but said its policy was under constant review, and that monitoring of radiation levels was being increased.
More than 70,000 people living inside the 20km zone have been evacuated, but another 136,000 living between 20-30km away have been told to stay in their homes. The US has recommended that its citizens stay at least 80km away.
Radiation fears have prevented authorities from collecting the bodies of as many as 1,000 people living in the evacuation zone who died in the 11 March earthquake and tsunami.
Kyodo news agency cited police sources as saying the corpses had been exposed to high radiation levels and would probably have to be decontaminated before they could be collected and examined by doctors.
Left as they were, the bodies could pose a health threat to relatives identifying them at morgues, the agency said. Cremating them could create radioactive smoke, while burying them could contaminate soil.
Nuclear safety officials said rising contamination in the sea near the plant pointed to a constant leak of radiation. On Thursday, Japan's nuclear and industrial safety agency said radioactive iodine near drains running from the plant was 4,385 times higher than the legal limit.
Experts said workers at the plant, 240km north of Tokyo, faced the problematic task of cooling overheating reactors with seawater while ensuring that contaminated runoff does not end up in the surrounding sea and soil.