The nation’s railway workers launched a work-to-rule strike on Monday, causing delays for subway commuters in the capital region. 

The Korea Railroad Corporation said Monday morning that parts of the capital region are witnessing delays in subway operations due to the slowdown. 

As of 8 a.m., about 40 trains on subway lines Nos. 1, 3 and 4, as well as the Suinbundang Line and others in the capital region, were operating five to 20 minutes behind schedule. 

However, the KTX bullet trains and non-express trains were operating normally. 

The Korean Railway Workers’ Union announced on Sunday that the work-to-rule action will last Monday to Friday, after which its members will decide whether to continue. 

Railway workers said they will adhere to the work manual by not rushing, placing train monitors when working along the tracks, and observing breaks and station stop times. 

The union is expected to launch an indefinite general strike early next month after holding a press conference Thursday.