Unionized workers of the Seoul subway system said that they will launch a second strike next week.

The union of Seoul Metro, which operates subway Lines One through Eight and part of Line Nine, said on Tuesday that it will hold a press conference on Wednesday morning in front of Seoul City Hall to announce the second strike.

The union plans to reveal details of the strike, which will reportedly begin next Wednesday. 

The unionized workers held a two-day “warning” strike last Thursday and Friday after failing to reach an agreement with management. 

The two sides have since continued negotiations but have yet to narrow differences.