In the January-March period, Hyundai posted a 14 percent on-year drop in sales in China, the world's biggest automobile market, with 196,119 vehicles. Kia also saw numbers there plunge 45 percent to 77,232 units during the same period, the companies said.

As local Chinese campaigns against South Korean-made products escalate, South Korean carmakers are bracing for weaker sales for the time being.

In efforts to offset losses in China, both Hyundai and Kia are looking to other markets.

"The row over the Terminal High Altitude Area Defense system between Seoul and Beijing could not be handled at a company level. But we will ride out these difficulties by boosting sales in other markets," a company official, who declined to be identified, said.

As for THAAD, China has opposed its deployment in South Korea as the country argues the system can be used against it. Seoul told Beijing that the missile battery is only aimed at countering missile threats from North Korea.

To further push up their combined market share in the Russian passenger car market from 21 percent in the first quarter, Hyundai seeks to strengthen marketing for the upgraded Solaris (or Accent) subcompact and the luxury G80 sedan. Kia plans to launch the latest iteration of its Morning city car and Rio (or Pride) subcompact this year.

The carmakers said they will take similar steps in other emerging markets such as Africa and Latin America by launching more customized models to secure a long-term growth engine.

To better react to local demand in growing markets, Kia has recently announced its plan to invest $1.1 billion won to build a 300,000-unit-a-year plant in India by 2019.

Hyundai plans to increase the annual output capacity at its commercial vehicle plant in Vietnam to 30,000 units from the current 10,000 to meet the growing demand for trucks and buses.

Hyundai has plants in the US, Brazil, India, China, Turkey, the Czech Republic and Russia. Kia runs assembly lines in the US, Mexico, China and Slovakia.

The two carmakers aim to sell a combined 8.25 million vehicles in global markets this year, up from 7.9 million units they sold last year. (Yonhap)