ULSAN (Yonhap News) -- Hyundai Motor Co., South Korea's largest carmaker, resumed weekend production at some of its assembly lines on Saturday, a move that could help the company make up for production shortfalls and resolve unfilled orders.

The resumption marked the first time Hyundai employees returned to the assembly lines in Ulsan for weekend work since March 4 when the carmaker ended its decades-long practice of running a graveyard shift.

The weekend work stoppage prevented the carmaker from producing 79,000 vehicles, costing it 1.7 trillion won ($1.5 billion) in lost production.

Under the new shift system, Hyundai employees work either from 6:50 a.m. to 3:30 p.m. or from 3:30 p.m. to 1:30 a.m. during weekdays and weekends.

Still, weekend production only resumed at three out of its five assembly lines in Ulsan, home to Hyundai's main production facility located some 410 kilometers southeast of Seoul.

It was not immediately clear when the two other assembly lines will be up and running on weekends.