The investigators told Kim in a letter that they were advising the United Nations to refer North Korea to the International Criminal Court (ICC), to make sure any culprits "including possibly yourself" were held accountable.

The unprecedented public rebuke and warning to a head of state by a U.N. inquiry is likely to further antagonize Kim and complicate efforts to persuade him to rein in his isolated country's nuclear weapons program and belligerent confrontations with South Korea and the West.

North Korea "categorically and totally" rejected the accusations set out in a 372-page report, saying they were based on material faked by hostile forces backed by the United States, the European Union and Japan.

Michael Kirby, chairman of the UN Commission of Inquiry, said he expected his group's findings to "galvanize action on the part of the international community".

"These are not the occasional wrongs that can be done by officials everywhere in the world, they are wrongs against humanity, they are wrongs that shock the consciousness of humanity," Kirby, a former chief justice of Australia, told journalists.

Referral to the Hague-based International Criminal Court is seen as unlikely given China's probable veto of any such move in the UN Security Council, diplomats said.

"Another possibility is establishment of an ad hoc tribunal like the tribunal on the former Yugoslavia," Kirby said.

The UN investigators also told Kim's main ally China that it might be "aiding and abetting crimes against humanity" by sending migrants and defectors back to North Korea to face torture or execution, a charge that Chinese officials dismissed.

"Strikingly similar" to Nazi era

The findings came out of a year-long investigation involving public testimony by defectors, including former prison camp guards, at hearings in South Korea, Japan, Britain and the United States.

Defectors included Shin Dong-hyuk, who gave harrowing accounts of his life and escape from a prison camp. As a 13-year-old, he informed a prison guard of a plot by his mother and brother to escape and both were executed, according to a book on his life called "Escape from Camp 14".

Kirby said that the crimes the team had catalogued were reminiscent of those committed by Nazis during World War Two. "Some of them are strikingly similar," he said.

"Testimony was given in relation to the political prison camps of large numbers of people who were malnourished, who were effectively starved to death and then had to be disposed of in pots, burned and then buried. It was the duty of other prisoners in the camps to dispose of them," he said.

“The number of North Korean officials potentially guilty of the worst crimes would be running into the hundreds,” he said.

The independent investigators' report cited crimes including murder, torture, rape, abductions, starvation and executions.

"The gravity, scale and nature of these violations reveal a state that does not have any parallel in the contemporary world," it said.

North Korea's diplomatic mission in Geneva dismissed the findings. "We will continue to strongly respond to the end to any attempt of regime-change and pressure under the pretext of 'human rights protection'," it said.

The two-page North Korean statement, in English, said the report was an "instrument of a political plot aimed at sabotaging the socialist system" and defaming the country.

Violations listed in the document and forwarded to Pyongyang for comment several weeks ago, "do not exist in our country".

(Agencies)

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