South Korea's railway union launched a 48-hour strike at 9 a.m. Thursday after failing to resolve a dispute with management over working conditions.

The Korean Railway Workers' Union, which claims about 25,000 members, said the walkout will be joined by metropolitan railway workers from Friday morning.

Union officials said negotiations with the state-funded Korea Railroad (KORAIL) fell through due to the management's refusal to compromise on wage hikes, the downsizing of full-time union members and the union's labor rights, according to Yonhap News Agency.

The KORAIL workers voted to strike late last month, with 76.6 percent supporting the walkout.

Only 60 percent of the normal workforce was manning local train and metropolitan subway services, but replacement staff were set to be mobilized incrementally, transportation authorities said.

"We will make utmost efforts to minimize passengers' inconvenience and take stern action against illegal activities (by the workers)," an official at KORAIL said.