Hyundai Motor Co. is expected to suffer cumulative production losses of more than 60,000 vehicles as its labor union steps up strike action amid stalled wage negotiations, industry sources said 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. The continued strikes are expected to bring cumulative production losses from last month through Aug. 25 to around 62,000 vehicles, with lost sales estimated at 2.6 trillion won ($1.85 billion), according to industry sources familiar with the matter. The labor dispute is adding pressure on Hyundai Motor as the automaker grapples with weakening global sales. Its worldwide sales fell 5.1 percent year-on-year to 318,454 vehicles in July, marking the 10th consecutive month of year-on-year declines.