Workers at Korean car maker GM Daewoo are poised to join the pay stoppages sweeping the country's motor industry.
Korean car workers want more pay
A Daewoo spokesman said workers at the firm, which is owned by General Motors, had voted for strike action, the AFP news agency reported.
Some 40,000 workers at Hyundai Motor began a four-day strike on Tuesday, while staff at its affiliate Kia Motors Corp staged a walk out.
Hyundai union officials have since said the strike may last beyond four days.
Union official Chang Gyu-ho said a longer strike would take place if there was no agreement during pay talks with management on Wednesday.
In the balance
"If the final offers are not satisfactory, we would have no
other choice but to launch a longer-term strike," he said.
Ssangyong Motor suffered a four-hour morning shutdown on Tuesday.
Vehicle makers are worried that higher salaries would threaten South Korea's competitive edge over Japanese and US car makers.
Auto workers are demanding higher wages and a say in whether plants move overseas.
The government is already battling to improve lacklustre domestic demand and business spending.
At Hyundai, employees are demanding a 10% pay increase and a bonus of 30% of profits.
Strikers have also said they will protest at the sending of more troops to Iraq following the execution last week of a South Korean hostage.
Staff at Kia are demanding a similar wage hike and an increase in bonuses.
As well as wage rises, Ssangyong's union wants the management to seek its approval before moving plants overseas.
At Daewoo, a company spokesman said: "The majority of the unionised workers have voted for the strike but it remains to be seen if it leads to a real industrial action."
South Korea usually sees increased strike action in summer. Last year, action at Hyundai went on for about 45 days.