Unionized workers at GM Korea Co., the South Korean unit of General Motors Co., on Tuesday entered a two-day partial strike, demanding higher wages.

GM Korea workers held a four-hour strike on Tuesday and plan to stage another four-hour walkout on Wednesday, GM union spokesman Dang Sung-geun said over the phone.

"Union leaders will hold a meeting on Thursday to decide on whether to enter another round of strikes," he said.

GM Korea and its union have held seven rounds of talks since July 9 over wages for the year of 2019. The union demanded a 5.7 percent hike in basic salary, performance-based bonuses worth two and a half months of wages and a cash bonus worth 6.5 million won (US$5,400) per worker, which was rejected by the company.

"At the outset of wage negotiations, the company explained that it is difficult to accept the union's requests for a salary increase and the payment of performance bonuses due to the unfavorable business environment both internally and externally and the fact that the company has not yet returned to profitability," the company said in a statement.

The 10,000-member union also asked the company to present its long-term plan for the operation of the No. 2 Bupyeong plant in Incheon, just west of Seoul.

The No. 1 Bupyeong plant has secured an output volume of the all-new Trailblazer sport utility vehicle. But the union argues that the No. 2 plant needs models to be produced in addition to the existing Malibu sedan and the Trax compact SUV, a company spokesman said.

GM Korea has three plants including the one in Changwon, 400 kilometers south of Seoul. Their combined output capacity reaches about 600,000 units. The company shut down a plant in Gunsan, 270 km south of Seoul, in May last year due to a low utilization rate.

From January to July, the carmaker's sales fell 7.2 percent to 263,023 vehicles from 283,432 units a year earlier.

To revive sluggish sales, it plans to introduce 15 new vehicles to the local market over the next five years. It launched the U.S.-made Equinox and the upgraded Chevrolet Spark minicar last year.

It plans to introduce the midsize Colorado pickup truck in the domestic market late this month and the Traverse SUV early next month. (Yonhap)