SEOUL South Korea's militant labor federation announced a general strike from Saturday in sympathy with rail workers, after police hauled away scores of strikers in a two-week dispute that has hit President Park Geun-hye's popularity ratings.
The Korean Confederation of Trade Unions (KCTU) has more than 690,000 members from sectors including construction and public transport and any stoppage could bring the country to a halt.
Workers with the state-run Korea Railroad walked off the job in protest against a decision to set up a unit to run a high-speed bullet train, which they say will lead to privatization and layoffs.
Hundreds of riot police stormed into the umbrella group's head office on Sunday in a bid to arrest union leaders. They detained about 130 strikers and confederation members.
"The KCTU will show our anger by action, not words, against infringement of KCTU," the confederation said in a statement on Monday, promising an all-out strike from Dec 28.
Freight trains are running at 54 percent normal frequency and passengers trains at 58 percent. That frequency will be reduced further this week.
The strikers want the company to withdraw the plan to set up a separate unit, and Park doesn't want to back down. She said the government would not give way in what has become the longest strike to hit the railway.
"We can't promise a future if we compromise without principles just because it is difficult," Park said on Monday.
The government has repeatedly denied planning to privatize the railway, but Park's approval ratings have sagged since the strike began.
A Gallup Korea poll showed on Friday that her approval ratings had fallen to 48 percent, the lowest since May.
Opposition parties blamed the police raid and urged the government to negotiate.
"People are getting tired and to regain trust... the government should engage in conversation and settle the situation," Democratic Party lawmaker Yoon Hu-duk told a parliamentary hearing.
Unionized workers from the loss-making rail operator have stymied efforts by previous administrations to take it private since the early 2000s.
(Reporting by Ju-min Park; Editing by Nick Macfie)