Unionized metal workers said Tuesday they will stage a one-day walkout later this week if automakers, including the top Hyundai Motor Co., do not accept their calls to count bonuses as part of base wages.

In December, the Supreme Court ruled that bonuses paid on a regular basis should count towards ordinary wages, which determine the size of other payments, such as overtime and severance pay.

Most companies including Hyundai and its smaller affiliate Kia Motors Corp., however, have been reluctant to abide by the new rules.  

"The Hyundai Motor Group should take its social responsibility and include bonuses as part of base pay," the Korean Metal Workers' Union said in a statement issued during a news conference.

The warning follows a breakdown of talks between the union and management of Hyundai Motor Group, the world's fifth-largest automotive conglomerate, earlier this month and a union vote last week that consolidated plans to go on strike.

Hyundai management has said pay hikes would have negative consequences at a time when high costs and low productivity exert a negative pull on the company's local operations.

The nationwide metal union said some 150,000 members, many of them from the Hyundai Motor Group, will join the strike this Friday. Another walkout will be staged next week if the business group does not accept their request for pay hikes. (Yonhap)