North Korea made the argument in a letter dated Wednesday from Ambassador Ja Song Nam to the UN General Assembly and Secretary-General Ban Ki-moon.
In the letter, the envoy branded Shin Dong-hyuk a "swindler" and a "parasite" who has been "pretending to be a 'survivor from the political prison camps' which are non-existent in the Democratic People's Republic of Korea."
Shin admitted this week that elements of his best-selling gulag survivor book "Escape from Camp 14" were inaccurate, although he stressed that the crucial details of his suffering and torture still stood.
In his letter, the ambassador charged that the commission report "was proved to be a fraudulent document fabricated by false testimonies of liars like Shin Dong-hyuk."
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"It is needless to say, all the 'resolutions' on the situation of human rights in the Democratic People's Republic of Korea forcibly adopted by the General Assembly on the basis of such false documents are invalid," wrote the ambassador.
The resolution was followed by the first-ever Security Council meeting on Pyongyang's rights record, which was held despite opposition from China.
The North Korean ambassador "strongly requested that the United Nations should take an impartial and fair stand" on his country.
Shin apologized on his Facebook page on Sunday, saying he had "forever wanted to conceal and hide part of my past."
The retractions refer to his account of being burned and tortured at age 13 after a failed attempt to escape the camp, which Shin now admits took place when he was 20.
Michael Kirby, the retired Australian judge who headed the UN Commission of Inquiry, said Shin's partial retractions were "substantially immaterial" to the panel's findings or recommendations.