South Korean military authorities have detected signs of activity at North Korea's major Yongbyon nuclear testing site as well as other nuclear facilities.

Multiple sources told KBS on Monday that South Korean military authorities have observed signs indicating activities to restore part of a launch pad in the Dongchang-ri missile launch site. 

The authorities also detected signs that uranium enrichment process is under way at the Yongbyon site and additional nuclear facilities. 

The sources said the "additional" facilities are not limited to a specific location, and refer to the North's overall force of weapons of mass destruction, hinting at resumed activities at multiple locations across the North.