Consumer agencies are urging the public to carefully inspect each and every food label before making purchases as the ingredients may have been processed in radiation-affected areas in Japan.
Due to contamination concerns, Seoul expanded its import ban to 50 products from Fukushima, site of a nuclear disaster in March 2011, and seven other nearby prefectures in Japan.
In addition to fish, the ban now includes leafy vegetables such as cabbage and broccoli. Those import restrictions, however, do not extend to processed foods or raw ingredients.
About seven tons of fishery products from Fukushima were imported in the span of one week last month, and local NGOs say the public may be at risk.
"Even the main ingredient in baby formula can be fish. There are many loopholes like these when dealing with processed foods," a spokesman for a NGO said.
Agricultural products from Japan are being thoroughly tested every day here to see if there are higher-than-average levels of radioactive cesium or iodine. However, experts say there's no effective way to detect other potentially harmful radioactive materials.