In October last year, China limited the number of powdered milk brands operating in the country to three, which will likely restrict market access to local companies wanting to sell to the large market. Currently, three South Korean companies export a total of 98 powdered milk products around the world.

The measures came right after Seoul decided to deploy the missile defense system, the Terminal High Altitude Area Defense (THAAD), on its soil aimed at deterring North Korean provocations, spurring speculation that it was in response to Seoul's THAAD decision. 

Also, Beijing has demanded higher commissions from foreign companies that seek to sell medical equipment there compared with local rivals.

The ministry said Chinese authorities have promised to respond to South Korea's claims after reviewing related issues with its own regulatory body.

Seoul's move came as it made an appeal to the WTO's service council in March to determine if Chinese measures on South Korean tourism and retail businesses conflict with WTO regulations.

China has been strengthening punitive measures against South Korean goods and businesses in such areas as tourism, retail and cultural content following the move to install the THAAD system. 

Beijing has banned tour packages to South Korea and delayed customs procedures on many goods.

Seoul claims that such punitive measures by China violate two main principles -- most favored nation (MFN) and national treatment (NT). Under the WTO framework, member countries have to give equal treatment to all trading partners in comparison with all other nations, while imported and locally produced goods should be treated equally. (Yonhap)