North Korea is not responding to regular contact through inter-Korean communication lines for the second day.

Seoul's defense ministry said Saturday the North did not answer the 9 a.m. opening call via the east and west sea military hotline.

Pyongyang was unresponsive to the military channel as well as that of the inter-Korean liaison office on Friday, and has yet to give any reason for the lack of response. 

A South Korean military official said they will continue to monitor the situation and remain open to all possibilities including technical issues on the North Korean side.

The two Koreas hold regular phone calls twice a day in the morning and afternoon via the joint liaison office as well as their military channel.

While the liaison office operates only on weekdays, the military hotline remains open on weekends as well for emergency purposes.