Tokyo residents were told yesterday that their tap water was unsafe for babies to drink, after radioactive iodine was detected at more than double the recommended maximum level.
The news came as the United States announced it was blocking the importation of food from districts near the stricken Fukushima nuclear plant after a series of contamination scares.
Water at a purification plant that serves the Japanese capital was found to contain radioactive iodine at more than twice the safe level for infants.
Officials insisted the water was fine for older residents to drink, but parents were cautioned against giving it to children less than 12 months old.
The Japanese government's chief spokesman, Yukio Edano, urged residents not to hoard bottled water. His comments follow multiple reports since the disaster began that shops have been running out of provisions because of panic buying.
Radiation has also been found in produce from districts around the Fukushima plant. The US Food and Drug Administration has now banned the importation of fresh fruit and vegetables, milk and milk products from four prefectures and other countries have stepped up the testing of food imports.
Mr Edano asked foreign countries not to overreact to radiation concerns. "We will explain to countries the facts and we hope they will take logical measures based on them," he said.
Japan has restricted the sale of certain foodstuffs because of radioactivity worries. Vegetables and untreated milk products from four districts around the plant can no longer be sent to market, and inspection regimes have been stepped up in other areas, including parts of greater Tokyo.
Levels of radioactive caesium in one vegetable were 164 times the permitted maximum. Eating it every day for 10 days would expose an individual to six months' worth of radiation under normal conditions.
Radioactivity has spread internationally from Fukushima, with particles found in Iceland, although experts have emphasised the low concentrations there pose no health risks.
There was another setback yesterday in the battle to stabilise the Fukushima plant, scene of the world's most serious nuclear incident for a quarter of a century, after cooling to reactors and spent fuel pools was disabled by the earthquake and tsunami of March 11. Black smoke billowed from the No 3 reactor, which has been the focus for concern since the crisis developed because its fuel mix contains highly toxic plutonium as well as uranium. Workers were forced to evacuate the plant temporarily when the plume developed, and a spike in radiation levels forced engineers to stop testing electrical systems at reactor No 2.
Only a day earlier hopes were raised that an end to Japan's nuclear crisis might be on the horizon when engineers completed the task of reattaching power cables to all six reactors.
The Japanese government yesterday released its first estimate of the cost of the earthquake and tsunami, putting the damage at 16 to 19 trillion yen (Dh0.73 trillion to Dh0.86 trillion). The cost, including repairs to damaged buildings and infrastructure, is expected to exceed that of any previous natural disaster.
As more mass burials took place, the death toll mounted, reaching 9,452. The total number missing was put at 14,671. Police have said the final death toll is likely to be around 18,000 although others have suggested it could rise higher.
