Unionized rail workers were returning to work Monday after a four-day general strike staged to demand better working conditions and an expansion of the KTX bullet train service.

The Korean Railway Workers' Union began the first walkout in about four years on Thursday, demanding the expansion of the KTX bullet train route to Suseo Station in southern Seoul, the starting point of another high-speed rail service SRT, as well as the full implementation of the four-team two-shift system.

The union brought its four-day strike to an end at 9 a.m. as planned.

KTX and other train services are expected to be fully back on track by Monday night after the collective action had reduced the operations of passenger trains to about 80 percent capacity nationwide.

While trains operations are on course for normalization, passengers are expected to experience difficulties in getting tickets and freight train services are expected to remain slow throughout the day.

The union is planning to go on another general strike in the near future although the exact timing has yet to be determined.

"The exact schedule will be determined depending on the reaction of the land ministry and the company (Korea Railroad Corp.)," a union official said. "The first strike was a kind of warning, but the second one will become an indefinite general strike," he said. (Yonhap)