North Korean security chiefs and possibly even Supreme Leader Kim Jong-un himself should face international justice for ordering systematic torture, starvation and killings comparable to Nazi-era atrocities, UN investigators said on Monday.

North Korean soldiers film the South Korean side of the Korean Demilitarized Zone last summer. A UN report into North Korea released Monday lists atrocities including murder, torture, rape, abductions, enslavement, starvation and executions. (REUTERS)

The investigators told Kim in a letter 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 UN 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 told Reuters.

Crimes on par with Second World War

Kirby told Reuters the crimes the team had catalogued were reminiscent of those committed by Nazis during the Second World War.

"Some of them are strikingly similar," he said.

Michael Kirby, chairperson of the Commission of Inquiry on Human Rights in North Korea, said North Korean leaders should face international justice. (Denis Balibouse/Reuters)

"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.

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.

"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 dismisses report

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".

An elderly man bows before the statues of North Korea's late leaders Kim Jong-il and his father Kim Il-sung, in Pyongyang, North Korea. (Yincent Yu/Associated Press)

The investigators said abuses were mainly perpetrated by officials in structures that ultimately reported to Kim - state security, the Ministry of People's Security, the army, the judiciary and Workers' Party of Korea.

"It is open to inference that the officials are, in some instances, acting under your personal control," Kirby wrote in the three-page letter to Kim published as part of the report.

'Deliberate starvation'

The team recommended targeted U.N. sanctions against civil officials and military commanders suspected of the worst crimes. It did not reveal any names, but said it had compiled a database of suspects from evidence and testimony.

Pyongyang has used food as "a means of control over the population" and "deliberate starvation" to punish political and ordinary prisoners, according to the team of 12 investigators.

Pervasive state surveillance quashed all dissent, it said.

North Korea's extermination of political prisoners over the past five decades might amount to genocide, the report added, although the legal definition of genocide normally refers to the killing of large parts of a national, ethnic or religious group.

Kirby warned China's charge d'affaires in Geneva, Wu Haitao, in a Dec. 16 letter that the forced repatriations of North Korean migrants and defectors might amount to "the aiding and abetting (of) crimes against humanity", the said.

Wu, in a reply also published in the report, said the fact that some of the North Korean migrants regularly managed to get back into China after their return showed that the allegations of torture were not true.

Human Rights Watch said it hoped the report would open the UN Security Council's eyes to the scale of atrocities.

"By focusing only on the nuclear threat in North Korea, the Security Council is overlooking the crimes of North Korean leaders who have overseen a brutal system of gulags, public executions, disappearances, and mass starvation," said executive director Kenneth Roth.