Kia Motors union workers plan to continue their strike action to push for higher wages and bonuses from South Korea's second largest automaker.

This followed three days of four hour strikes last week at the three domestic plants in Gwangmyeong and Hwaseong near Seoul and in Gwangju in the south.

Union leaders said they would extend their partial strike for several days despite the COVID-19 pandemic, including three days this week, after they failed to reach an agreement with management.

Union spokesman Hwang Hyo-dong said: "Kia Motors has not contacted the union to narrow the differences over wages and performance based bonus expectations following 14 rounds of wage negotiations."

The union is demanding a KRW120,000 (US$104) increase in monthly basic pay, 30% of the company's annual operating profit in performance based pay plus an increase in the retirement age from 60 to 65 years.

Kia has offered workers 1.5 months' salary in additional performance related pay, a special COVID-19 allowance of KRW1.2m plus KRW200,000 in gift certificates and company shares in lieu of freezing wages for the year which the union has rejected. 

Unions are also demanding that Kia build a modular components plant for electric and hydrogen vehicles in house rather than sourcing these parts from a new plant being built by Hyundai Motor Group affiliate Hyundai Mobis.