MOSCOW (Sputnik) — The new information comes shortly after media reports suggested Pyongyang was preparing for a new nuclear test.
"An increased movement of people and cars has been spotted at the nuclear site. North Korea appears to be in the process of digging another tunnel," the official told the South Korean Yonhap news agency on the condition of anonymity.
North Korea then withdrew from the talks, declared itself a nuclear power in 2005, and conducted nuclear tests in 2006, 2009 and 2013. Pyongyang has never made public how many nuclear weapons it possesses.
Pyongyang’s nuclear activities have received international condemnation.