Seoul: Hyundai Motor is expected to suffer cumulative production losses of more than 60,000 vehicles as its labour union steps up strike action amid stalled wage negotiations, industry sources said on Wednesday. 

The automaker's union said it will stage four-hour partial strikes on Wednesday and Thursday, followed by an eight-hour full-scale strike on Friday, its first such walkout in 10 years.

The union also plans to stage four-hour partial strikes next Monday and Tuesday, extending its latest walkout to five days, reports Yonhap news agency.

The continued strikes are expected to bring cumulative production losses from last month through August 25 to around 62,000 vehicles, with lost sales estimated at 2.6 trillion won (US$1.85 billion), according to industry sources familiar with the matter.

The latest walkout comes after management and the union failed to narrow their differences over wages. The two sides last held their 16th round of negotiations earlier in the day.

The 40,000-member union is demanding a 149,600-won (US$105.6) increase in monthly base pay and a performance-based bonus equivalent to 30 percent of the company's net profit for last year.

The company, however, has offered an 80,000-won increase in monthly base pay, a performance bonus equivalent to 350 percent of monthly salary plus 10 million won, as well as 15 shares of company stock.

The labour dispute is adding pressure on Hyundai Motor as the automaker grapples with weakening global sales.

Hyundai Motor said earlier this month that its global sales declined from a year earlier in July, weighed down by production disruptions caused by partial strikes and weaker demand.

The South Korean automaker sold 318,454 vehicles worldwide last month, down 5.1 percent from a year earlier.

Overseas sales slipped 3.2 percent on-year to 270,341 units, while domestic sales dropped 14.4 percent to 48,113 units.

The decline marked the company's 10th consecutive month of falling global sales.

Hyundai Motor attributed the weaker performance to production disruptions caused by a partial labour strike in July and customers delaying purchases ahead of the launch of new models.