TOKYO (AFP) – Tokyo on Wednesday warned that radioactive iodine over twice the safe level for infants had been detected in its tap water due to the disaster at a quake-hit nuclear plant northeast of Japan's capital.
The news compounded fears over the impact of the crippled Fukushima power station that also led the government to ban farm produce from areas near the charred complex, where emergency crews were battling to prevent a meltdown.
Workers were evacuated from part of the nuclear power station on Wednesday after dark smoke was seen rising from one of the reactors, plant operator TEPCO said.
The United States blocked imports of dairy and other produce from areas near the plant, which has been belching radiation since it was hit by a powerful quake and tsunami on March 11, followed by a series of explosions and fires.
France urged the European Union to also control Japanese food imports.
In one Tokyo ward, a water sample contained 210 becquerels of iodine per kilogramme, more than double the legal limit, a city official said at a press conference -- news that triggered a 1.6 percent dive on the Tokyo stock market.
"Under government guidelines, water containing a radioactive substance of more than 100 becquerels per kilogramme should not be used for milk for babies," the city official told reporters.
The government advised residents throughout the city to avoid using tap water to make infant formula until further notice.
Prime Minister Naoto Kan earlier ordered a stop of shipments of untreated milk and vegetables including broccoli, cabbage and parsley from areas near the Pacific coast plant, about 250 kilometres (155 miles) northeast of Tokyo.
Farm produce shipments were halted from Fukushima and three nearby prefectures -- Ibaraki, Tochigi and Gunma -- while radiation monitoring of farm and seafood products was stepped up in six others, officials said.
The new inspection zone extends to Saitama and Chiba, part of the greater Tokyo urban sprawl that is home to more than 30 million people.
The health ministry said radioactivity drastically exceeding legal limits had been found in 11 kinds of vegetable grown in Fukushima.
Radioactive caesium at 82,000 becquerels -- 164 times the legal limit -- was detected in one type of leaf vegetable, it said.
The ministry said that if people eat 100 grams (four ounces) a day of the vegetable for about 10 days, they would ingest half the amount of radiation typically received from the natural environment in a year.
"Even if these foods are temporarily eaten, there is no health hazard," said top government spokesman Yukio Edano, following reports that some products may have already entered the market.
"But unfortunately, as the situation is expected to last for the long term, we are asking that shipments stop at an early stage, and it is desirable to avoid intake of the foods as much as possible."
Even if the short-term risk is limited for now, scientists pointing to the 1986 Chernobyl disaster warn that some radioactive particles concentrate as they travel up the food chain and stay in the environment for decades.
The US Food and Drug Administration said it had placed an import alert on all milk, dairy products, fresh vegetables and fruits from four prefectures.
"In addition, FDA will continue to flag all entries from Japan in order to determine whether they originated from the affected area," it said. "FDA will test all food and feed shipments from the affected area."
France urged the European Commission to impose "systematic controls for all fresh produce reaching Europe's borders" from Japan, while stressing that it was not calling for a total embargo on Japanese food products "at this stage".
Around Asia, many Japanese restaurants and shops are reporting a decline in business and governments have stepped up radiation checks on the country's goods. Tainted fava beans from Japan have already cropped up in Taiwan.
Japan -- a highly industrialised and mostly mountainous island nation -- is a net food importer. According to the European Commission, the EU imported 9,000 tonnes of fruits and vegetables from Japan in 2010.
In Japan, any further food shortages threaten to compound the misery for hundreds of thousands made homeless by the 9.0-magnitude quake and the jet-speed tsunami it spawned that erased entire communities.
The confirmed death toll rose Wednesday to 9,408, and Japan holds out little hope for 14,716 officially listed as missing.
Japan estimated the economic cost at up to 25 trillion yen ($309 billion).
As grieving survivors huddled in evacuation shelters amid the rubble of their former lives, their fate was overshadowed by the struggle to avert another massive catastrophe -- a full nuclear meltdown at Fukushima.
Fire engines and giant concrete pumps have poured thousands of tonnes of seawater onto its reactors and into spent fuel rod pools, to cool them and stop fuel from being exposed to the air and releasing large-scale radiation.
Engineers hope to restart the cooling systems of all six reactors that were knocked out by the 14-metre (46-foot) tsunami, and they have already reconnected the wider facility to the national power grid.
As the engineers forged on with their dangerous and complex task at the 1970s-era plant, more nerve-jarring aftershocks hit nearby.
In Vienna, the UN's International Atomic Energy Agency said radiation continues to leak from the site.
"The question is, where exactly is it coming from: from the primary containment vessels or from the spent fuel ponds," said James Lyons, IAEA head of nuclear installations safety.
"Without the ability to go up there and actually poke around, it's hard to determine."