Late-night talks to end a rail strike in South Korea have failed as the country returns to work after a public holiday and the new school year starts.
Protesting railway staff say their demands have gone unheard
More than 16,000 staff stopped work on Wednesday over pay and conditions and the sacking of colleagues.
State-run rail operator Korail cut half its services but disruption was mitigated by lighter holiday demand.
Technically the strike is illegal as it went to arbitration after direct talks failed on Tuesday.
Police have issued arrest warrants for three union leaders and are seeking warrants for eight more, according to an official at police headquarters.
RAIL STRIKERS' DEMANDS
Better working conditions
Reinstatement of workers sacked earlier
A railway corporation official quoted by Reuters news agency said Korail would probably have to "bring in the police to break up the strike".
An official in the railway workers' union, Paek Nam-hee, said it had tried to avert a strike by agreeing to put off a stoppage planned for December in the hope of finding a negotiated solution.
"But unfortunately, the corporation has not budged at all and now the trains have stopped," he added.
Experts said there could be chaos on Thursday as commuters return to work.
As of early evening on Wednesday, the walkout had forced the cancellation of 79% of long-distance passenger trains and 84% of cargo trains, Korail said.
Korail normally carries more than 2.5 million passengers a day.
It has recruited retirees, non-unionised staff and military personnel to provide a skeleton service.
The government has invoked special powers governing industries vital to the national economy to end disputes at Korean Air and Asiana Airlines over the last year.