Unionized workers at Renault Samsung Motors Co. went on a partial strike to demand higher wages, a company spokesman said Monday. Some workers downed tools for two hours earlier Monday while others plan to start the four-hour walkout from 7:45 p.m., Renault Samsung spokesman Koh Jae-yong said. Some 1,800 unionized workers already walked out for four hours earlier this month. The local unit of French automaker Renault SA said it has not been able to produce about 400 vehicles due to the partial walkout. \"There is a possibility that the management and union may narrow their differences on basic salaries,\" a key issue in the partial strike, Koh said, without elaborating. Repeated calls to the union seeking comment went unanswered. Last year, some 800 employees left the company under the carmaker\'s first voluntary retirement program meant to cut costs since its foundation in 2000. The carmaker said earlier this month that its May sales dropped 22.6 percent from a year ago due to a slump in both domestic and overseas demand. Renault Samsung sold 9,572 vehicles last month, compared with 12,373 units a year ago, the company said in a statement.