Japanese food products have long been regarded as synonymous with "safety" and "security" in other parts of Asia, but their reputation is now at stake as radioactive materials far exceeding legal limits have been found in farm produce.

The detection of radioactive materials prompted the U.S. Food and Drug Administration on Tuesday to announce a ban on imports of dairy products and vegetables from the area near the crisis-hit Fukushima No. 1 nuclear power plant.

Countries in Asia and authorities in the Russian Far East have stepped up screening of Japanese food imports for radioactive contamination, while seawater has also been contaminated near the nuclear plant.