The UN Command(UNC) has refused to allow a South Korean train to cross into North Korea, thwarting an inter-Korean plan to conduct a joint survey on a section of the Gyeongui railway.  

Sources say the UNC refused to allow the train and South Korean officials aboard it to cross the Military Demarcation Line(MDL) last Thursday, noting their failure to notify the travel plan within a time limit. 

Notifying the UN Command up to 48 hours in advance is required to cross the MDL. South Korea had reported the plan but only 24 hours in advance due to a delay in consultations with the North. 

Observers say the command's decision is unusual and may indicate the U.S.' dissatisfaction with South Korea pressing ahead with improving economic ties with North Korea, noting that the command has previously been flexible in applying the travel notice rule. 

Regarding the joint railway inspection, a Unification Ministry official said that South Korea is closely discussing the issue with the U.S. and the North.