An extended strike by rail union workers began to take a heavy toll on passenger train services nationwide, as the replacement staff have been rushed to man freight trains, Yonhap News reported Sunday.

With the indefinite strike by unionized KORAIL workers entering its fourth day, operations of passenger trains were cut back to about 60 percent of their normal capacity, while freight train services were running at about 30 percent of capacity, up from less than 10 percent last week, the agency quoted the state-owned company as saying
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The union's 16,000 workers walked out on Thursday after negotiations over pay and work conditions fell through.

"We will do everything we can to minimize inconvenience and mobilize all available workers to operate trains as normally as possible," a KORAIL official was quoted as saying.

KORAIL transferred some of its remaining staff to freight services, after their operation rate on the first day of the stoppage dropped to 5 percent of their daily capacity, or 15 runs compared to an average 300.

Freight services were set to rebound to 60 runs on Sunday, enlivening major logistics hubs, such as the Uiwang Inland Container Depot near Seoul, export freight bases on southern coasts and resuming much of the cement and coal transportation in the central part of the country, KORAIL said.

But inconveniences by commuters and travelers are expected to continue for the time being, as a growing number of the Saemaeul and Mugunghwa passenger trains, cheaper alternatives to the KTX bullet train, have been canceled and delayed. High-speed KTX train services and city subways continued to operate at normal capacity.