TOKYO - (AP) - Radiation leaking from Japan's tsunami-damagednuclear power plant has caused Tokyo's tap water to exceed safetystandards for infants to drink, officials said Wednesday, sendinganxiety levels soaring over the nation's food and water supply. Residents cleared store shelves of bottled water after TokyoGov. Shintaro Ishihara said levels of radioactive iodine in tapwater were more than twice what is considered safe for babies.Officials begged those in the city to buy only what they needed,saying hoarding could hurt the thousands of people without anywater in areas devastated by the March 11 earthquake and tsunami. "I've never seen anything like this," clerk Toru Kikutakasaid, surveying the downtown Tokyo supermarket where the entirestock of bottled water sold out almost immediately after the newsbroke, despite a limit of two, two-liter bottles per customer. The unsettling new development affecting Japan's largest city,home to around 13 million people, added to growing fears over thenation's food supply. Radiation from the Fukushima Dai-ichi nuclear plant has seepedinto raw milk, seawater and 11 kinds of vegetables, includingbroccoli, cauliflower and turnips, from areas around the plant. TheU.S. Food and Drug Administration said it was halting imports ofJapanese dairy and produce from the region near the facility. HongKong went further and required that Japan perform safety checks onmeat, eggs and seafood before accepting those products. Officials are still struggling to stabilize the nuclear plant,which on Wednesday belched black smoke from Unit 3 and forced theevacuation of workers, further delaying attempts to make neededrepairs. The plant, 140 miles north of Tokyo, hasbeen leaking radiation since the quake and tsunami knocked out itscrucial cooling systems. The crisis is emerging as the world's most expensive naturaldisaster on record, likely to cost up to $309 billion, according toa new government estimate. Police say an estimated 18,000 peoplewere killed. Concerns about food safety spread Wednesday to Tokyo afterofficials said tap water showed elevated radiation levels: 210becquerels of iodine-131 per liter of water - more than twice therecommended limit of 100 becquerels per liter for infants. Anothermeasurement taken later at a different site showed the level was190 becquerels per liter. The recommended limit for adults is 300becquerels. "It is really scary. It is like a vicious negative spiral fromthe nuclear disaster," said Etsuko Nomura, a mother of twochildren ages 2 and 5. "We have contaminated milk and vegetables,and now tap water in Tokyo, and I'm wondering what's next." Infants are particularly vulnerable to radioactive iodine, whichcan cause thyroid cancer, experts say. The limits refer tosustained consumption rates, and officials urged calm, sayingparents should stop giving the tap water to babies, but that it wasno problem if the infants already had consumed small amounts. They said the levels posed no immediate health risk for olderchildren or adults. The death toll from the disaster has continued to rise, with morethan 9,500 bodies counted and more than 16,000 people listed asmissing.