The party's secretary was siting South Korea's intelligence service, according to the Yonhap news agency.
"While North Korea has closed its Punggye-ri test site and dismantled some of the facilities at the Tongchang-ri missile test site as part of denuclearization initiative, intelligence activities and preparations for the visit of a foreign inspection group have been noticed," the secretary said as quoted by the agency.
READ MORE: US Attempted to Put Brakes on Economic Cooperation Between Two Koreas — Reports
Over the past few months, Pyongyang has demonstrated willingness to reduce tensions with Seoul and work toward the denuclearization of the peninsula. Kim attended three historic summits with South Korean President Moon Jae-in and held an unprecedented meeting with US President Donald Trump, pledging to achieve lasting peace in the region.