Japan's trade ministry said Tuesday the number of "problematic" anti-dumping measures is rising, citing South Korean stainless steel and U.S. steel sheet trade cases as among priority issues to tackle.

In its annual report on unfair trade practices, the Ministry of Economy, Trade and Industry newly cited eight cases of anti-dumping measures by China, the United States, South Korea, India and Turkey on Japanese products that are likely to be incompatible with World Trade Organization rules.

A ministry official said more countries are moving to impose anti-dumping measures to protect domestic industries from low-priced products, such as oversupplied steel and chemical products.

The eight problematic cases included the launch of an anti-dumping investigation by the United States on Japanese steel sheets and by China on Japanese plastic products widely used for food packaging, both in April last year.

In the case of Japanese steel exported to the United States, the investigation covers a type of product not competing with affected domestic products, the ministry said. As for the Chinese case, no logical explanation has been presented on the effects of imports on China's domestic market, it said.

The ministry also said South Korea's current process looking into whether tariff imposition on Japanese stainless steel should be extended is also likely to be incompatible with WTO rules.

The ministry said it may consider reporting the South Korean case to the WTO if the situation does not improve through negotiations.

It also questioned China's cybersecurity law, set up last November and coming into force next month, as it may coerce foreign firms to follow regulations and standards incompatible with WTO rules.