Kim Jong-Un's officials vow to tear up the 1953 armistice if the US presses ahead with proposed sanctions and continues military drills.
North Korea has vowed to scrap the 1953 ceasefire should the US continue to press for UN sanctions over military tests and continue its defence program with South Korea.
The move came amid reports that Washington and Beijing have approved a draft of punishing sanctions for a UN Security Council resolution responding to North Korea's nuclear test, on 12 February. The draft is expected to be circulated at the UN on Tuesday.
Meanwhile around 200,000 Korean troops and 10,000 US forces have begun their annual "Foal Eagle" exercise, one of the world's largest military drills, which began at the start of this month and is due for completion at the end of April.
A spokesman for the North Korean army was quoted on state television as saying: "The war exercise being done by the United States and the puppet South Korea is a systematic act of destruction."
He added: "We will be suspending the activities of the KPA representative office at Panmunjom that had been tentatively operated by our army as the negotiating body to establish a peace regime on the Korean peninsula."
The move comes at a crucial time, less than three months after a controversial military test of a long range rocket that ignited fears of renewed hostilities between the two sides. North and South Korea are technically still at war after their 1950-1953 conflict ended with an armistice, but not a peace treaty. They are separated by a demilitarised zone, one of the most heavily fortified borders in the world.
The state of North Korea's million-man army, one of the world's largest, is studied closely both in South Korea and in Washington, which keeps more than 28,000 troops in South Korea as a deterrent.
Further isolationism: 'Hotline' goes cold
Officials in North Korea are also threatening to disconnect a diplomatic hotline connecting Panmunjom to Washington. The move, largely seen as a symbolic gesture, is likely to worry UN diplomats who will draft proposals next week.
The announcement is also an escalation from the start of the year when the North Korean leader Kim Jong-un called for better ties with South Korea.
During the new year broadcast, made on state television after the country successfully launched a long-range rocket, Kim warned how continued confrontation would ultimately lead to "nothing but war".
12 February 2013
04 January 2013
- North Korea vows to tear up Korean war ceasefire agreement The Guardian
- North Korea: a nuclear tragedy which plays out as a comedy Independent Voices
- Meeting Shin Dong-hyuk The Spectator