Countries across the world shunned Japanese food imports Thursday as radioactive steam leaked from a disaster-struck nuclear plant, straining nerves in Tokyo.
The grim toll of dead and missing from Japan's monster quake and tsunami on March 11 topped 26,000, as hundreds of thousands remained huddled in evacuation shelters and fears grew in the megacity of Tokyo over water safety.
The damage to the Fukushima nuclear plant from the tectonic calamity and a series of explosions has stoked global anxiety. The United States and Hong Kong have already restricted Japanese food, and France wants the EU to do the same.
Russia ordered a halt to food imports from four prefectures -- Fukushima, Gunma, Ibaraki and Tochigi -- near the stricken plant 250 kilometres (155 miles) northeast of Tokyo.
Moscow also placed in quarantine a Panama-flagged cargo ship that had passed near the plant and put its 19 crew under medical supervision after detecting radiation levels three times the norm in the engine room.
Australia banned produce from the area, including seaweed and seafood, milk, dairy products, fresh fruit and vegetables.
It said, however, that Japanese food already on store shelves was safe, as it had shipped before the quake, and that "the risk of Australian consumers being exposed to radionuclides in food imported from Japan is negligible".
Singapore also suspended imports of milk products and other foodstuffs from the same four prefectures and Canada implemented enhanced import controls on products from the quartet.
The Philippines banned Japanese chocolate imports.
"Food safety issues are an additional dimension of the emergency," said three UN agencies in a joint statement issued in Geneva, pledging they were "committed to mobilising their knowledge and expertise" to help Japan.
Japan was taking the right actions, said the International Atomic Energy Agency, World Health Organization, and Food and Agriculture Organization.
"Food monitoring is being implemented, measurements of radioactivity in food are taking place, and the results are being communicated publicly."
In greater Tokyo, an urban sprawl of more than 30 million people, strong aftershocks overnight and in the morning served as uncomfortable reminders that Japan's capital itself is believed to be decades overdue for a mega-quake.
The anxiety was compounded by the Tokyo government's revelation Wednesday that radioactive iodine in the drinking water was more than twice the level deemed safe for infants, although it remained within safe adult limits.
The news triggered a run on bottled water in shops and the city's ubiquitous vending machines, while the Tokyo government started to give families three 550-millilitre (18.5-ounce) bottles of water per infant.
A measurement on Thursday was in the safe zone for infants again, officials said, but this was not enough to soothe all parents of young children.
"I don't want to panic," Kazuko Hara, 39, told AFP as she collected her three allotted bottles of water in Tokyo's Bunkyo ward.
"I will use bottled water for now. If we run out, I will use tap water. Experts say it's OK. But when you see people buying bottled water at stores and emptying store shelves, that makes you worry again."
Japan's government has also halted shipments of untreated milk and vegetables from Fukushima and three adjoining prefectures, and stepped up radiation monitoring at another six, covering an area that borders Tokyo.
The health ministry has detected 82,000 becquerels of radioactive caesium -- 164 times the safe limit -- in the green vegetable kukitachina, and elevated levels in another 10 vegetables, including cabbage and turnips.
At the source of the radiation -- the Fukushima plant located on the Pacific coast -- white smoke could be seen wafting from four of the six reactors.
Fire engines again aimed their high-pressure water jets at the number three reactor, a day after a plume of dark smoke there forced workers to evacuate, in their bid to avert a full meltdown that would release greater radiation.
Highlighting the risks taken by the emergency crew, three workers were exposed to high radiation -- at least 170 millisieverts.
Two of them were sent to hospital after they stepped into a puddle of water that reached the skin on their legs despite their radiation suits.
Engineers have now linked up an external electricity supply to all six reactors and are testing system components and equipment in an effort to soon restart the tsunami-hit cooling systems and stabilise the reactors.
On Thursday, they partially restored power to the control room at reactor number one.
The grim statistics from Japan's worst post-war disaster kept on rising, with 9,737 now confirmed dead and 16,423 listed as missing by national police.
Scientists at the Port and Airport Research Institute meanwhile found that the tsunami that swallowed entire towns was even bigger than first thought. In devastated Ofunato, Iwate prefecture, it topped 23 metres (76 feet).