Hyundai Motor's labour union said on Monday employees plan to halt work for three days this week following a series of partial strikes that have cost the Korean giant more than $1-billion in lost sales.
Hyundai Motor and its affiliate Kia Motors, which together form the world's fifth largest automaker, are struggling to reach agreement with their unions over demands for higher wages and an end to night shifts.
The latest strikes, planned for Tuesday through Thursday, will add to partial stoppages over the past six weeks that have cost the company 2.1-trillion won ($1.85-billion) in lost production of 109 474 vehicles.
Hyundai's 44 000-strong union has staged partial strikes 10 times for up to four hours since stoppages began on 13 July, and Kia has seen similar industrial action.
Hyundai said the prolonged dispute could undercut sales in the United States because inventories stood at record-low levels.
Total exports of Hyundai and Kia vehicles from South Korea fell 23 percent to 120 493 vehicles in July from 156 200 the previous month.
Both companies said inventories were at unprecedentedly low levels, causing a shortage of vehicles for US dealerships.
"The situation is still manageable, but prolonged strikes are feared to aggravate a shortage of vehicles and hurt sales in the US market," a Hyundai official told AFP on condition of anonymity.
Hyundai has predicted steady growth in the second half thanks to robust overseas sales, especially in the United States.