North Korea has threatened "merciless punishment" against South Korea if it goes ahead with plans to open a UN field office in Seoul for monitoring the North's human rights record.
The Committee for Peaceful Reunification of Korea (CPRK), a state body handling inter-Korean affairs, said late on Monday that the office was an "unforgivable provocation" and would become a "first-strike target."
The United Nations first proposed opening the field office in May last year, following a searing report by a UN commission that concluded North Korea was committing human rights violations "without parallel in the contemporary world".
The report formed the basis of a resolution adopted by the UN General Assembly in December, urging the Security Council to consider referring Pyongyang to the International Criminal Court.
The field office is expected to open in Seoul sometime in the first half of this year.
"As soon as the nest for an anti-DPRK (North Korea) smear campaign is in place in the South, it will immediately become the target for our merciless punishment," the CPRK said in a statement carried by the North's official KCNA news agency.
The statement said the South was committing a "heinous crime" against the Korean people by helping whip up international sentiment over Pyongyang's human rights record.
Pyongyang has categorically rejected the findings of the UN commission, labelling it a work of fiction authored by the United States and its allies.
Based on the testimony of hundreds of North Korean exiles, the commission detailed a vast network of prison camps holding up to 120,000 people and documented cases of torture, summary executions and rape.