Updated from 4:27 a.m. EDT with more information on the nuclear crisis in Japan.

NEW YORK (

TheStreet

) -- Tokyo stores have began rationing goods and bottled water was disappearing off shelves Thursday after hazardous radiation levels were detected in Japanese tap water, milk and vegetables,

The Associated Press

reported.

A shopper walks past empty super market shelves in Ichinoseki, Japan on Thursday as food and water becomes scarce.

Tokyo authorities said water at a purification plant for Tokyo was contaminated with levels of radioactive iodine that were more than twice the safety level for infants.

Shintaro Ishihara, Tokyo's governor, said however that the radiation level posed no immediate health risk, and water could still be used, but recommended it not be for infants.

Even after the government advised residents not to panic, frightened Tokyo residents flocked to stores throughout Japan to stock up on bottled water and other staples such as rice, instant noodles and milk, the

AP

reported.

"The first thought was that I need to buy bottles of water," Reiko Matsumoto said. Matsumoto, a mother of a 5-year-old, was one of the many Japanese residents who rushed to the store to stock up on supplies. "I also don't know whether I can let her take a bath."

As a precautionary measure, the United States and other countries have blocked some food imports from Japan.

"This is without doubt, an effect of the Fukushima Dai-ichi plant," a Tokyo metropolitan government official said Wednesday, referencing the nuclear plant that was damaged in the earthquake and ensuing tsunami on March 11,

Reuters

reported.

The U.S. Food and Drug Administration said it was stopping imports of milk, vegetables and fruit from four prefectures in the vicinity of the stricken nuclear plant after Japan discovered radiation above safety levels in 11 types of vegetables from the area,

Reuters

reported.

Australia also said it was halting imports of Japanese dairy and produce from the region.

Hong Kong also banned produce and milk imports from the disaster zone after authorities found radiation levels in spinach and turnips up to 10 times over the safety limit, according to Japan's

Jiji

news agency.

Canada said it would upgrade controls on imports of Japanese food products,

AP

reported.

In Iceland, trace amounts of radioactive iodine were found in the air but they were "less than a millionth" of levels found in European countries in the wake of the 1986 Chernobyl disaster, officials said,

AP

reported.

The detection of radiation in food and water has sparked global concerns despite officials' assurances that the levels posed no immediate danger.

The contaminated tap water would "have to be drunk for a whole year in order to accumulate to 1 millisievert," TEPCO said, referring to the standard measurement unit of radiation,

Reuters

reported. People are exposed to between 1 and 10 millisieverts every year from radiation caused by substances in the air and soil.

Japan's Chief Cabinet Secretary Yukio Edano urged Japanese residents and the world not to overreact.

"We have measures in place that keep products with radiation above a certain level out of circulation," he said at a news conference,

Reuters

reported. "That means anything in circulation is safe. This is not necessarily well understood by other countries."

Workers at Japan's tsunami-damaged Fukushima Dai-Ichi nuclear power complex were evacuated on Wednesday after black smoke was spotted rising from Unit 3, Tokyo Electric Power, the operator of the plant, said.

"We don't know the reason" for the smoke, said Nuclear and Industrial Safety Agency official Hidehiko Nishiyama,

AP

reported.

On Thursday, two workers at the Dai-ichi plant were hurt when their feet came in contact with radioactive elements while laying electrical cables in one unit, said a spokesman for the Nuclear and Industry Safety Agency.

Power plant workers have been working tirelessly to cool the overheating reactors ever since the diesel generators, which provide backup electricity to the plant's cooling system, were completely knocked out by the 9.0-magnitude earthquake and ensuing tsunami on March 11.

Workers were able to connect power lines to the six reactor units at the complex on Tuesday only to discover that a number of the cooling system's main pumps at Unit 2 weren't functional.

TEPCO placed emergency orders for new pumps to replace the broken equipment, but it wasn't immediately known how long it would take for them to be delivered.

Meanwhile, emergency crews continue to clear the rubble and debris left behind by the devastating earthquake and tsunami that hit Japan killed up to 20,000 people, according to estimates. The Japanese government said Wednesday that rebuilding efforts could cost up to $309 billion.

The death toll in Japan stood at about 9,811 as of Thursday, according to reports, while more than 17,500 were missing.

--

Written by Joseph Woelfel and Theresa McCabe.

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