Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

Atrocities committed by North Korea against its own people are "strikingly similar" to those perpetrated by the Nazis during World War II, the head of a United Nations panel said Monday after publishing an unprecedented report.

The year-long investigation called for urgent action by the international community to stop allleged crimes against humanity committed by Kim Jong Un and his regime.

"At the end of the Second World War so many people said, 'If only we had known, if only we had known the wrongs that were done in the countries of the hostile forces,'" inquiry chairman Michael Kirby told a press conference in Geneva after releasing the report.

"Well now the international community does know … there will be no excusing the failure of action because we didn't know - we do know," Kirby said, holding up a copy of the report.

The report comes a year after the U.N. Human Rights Council set up the Commission of Inquiry into the D.P.R.K. (Democratic People's Republic of Korea) in March last year. It said hundreds of North Korean officials, "right up to the highest level of state," were potentially responsible for what it called "unspeakable atrocities" against their own people.

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

The commissioners also wrote a letter to Kim Jong Un informing the North Korean ruler that they would be recommending referring his country to the International Criminal Court (ICC). This was "to render accountable all those, including possibly yourself, who may be responsible for the crimes against humanity referred to in this letter and in the commission’s report."

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

The report also warned China that it may be "aiding and abetting crimes against humanity" with its policy of forcibly repatriating North Koreans who fled across its borders. Kirby wrote another letter to China's charge d'affaires in Geneva, Wu Haitao, saying that those caught fleeing to China and sent back to North Korea were likely to be tortured or executed. Haitao replied to say that this was not true.

With its pleas for cooperation flatly ignored by North Korea, the inquiry compiled their 400-page report by interviewing hundreds of victims and experts over the past year. These people spoke about the indoctrination, starvation, and torture endured in everyday life in North Korea.

But the report also shed new light on the country's darkest side - its labor camps.

As many as 120,000 North Koreans are thought to be imprisoned across the country, many of them in four large camps. This number may have shrunk in recent years, according to the report, but only because many of the inmates have been murdered or starved to death.

People and their families are held for arbitrary crimes such as "gossiping" about the state.

The abject life in these prisons has been documented before by rights groups such as Amnesty International, which last year released satellite imagery and first-hand accounts from escaped prisoners.

They said inmates were raped, tortured, given forced abortions and forced to dig their own graves before being murdered with hammers by guards.

Satellite imagery of Political Prison Camp No. 25, in Chongjin, North Hamgyong Province. Digital Globe

The U.N. report contains more of this harrowing testimony, which it says is tantamount to "extermination, murder, enslavement, torture, imprisonment, rape, forced abortions and other sexual violence." It compared conditions to camps run by the Nazis during World War II and gulags set up in Soviet Russia.

Comparing the crimes committed by North Korea to the Nazis, Kirby told Reuters on Monday: "Some of them are strikingly similar."

The report added: "The unspeakable atrocities that are being committed against inmates of the 'kwanliso' political prison camps resemble the horrors of camps that totalitarian states established during the 20th century.

"The institutions and officials involved are not held accountable. Impunity reigns. The gravity, scale and nature of these violations reveal a state that does not have any parallel in the contemporary world."

In a statement to Reuters, North Korea said it "categorically and totally rejects the report," which it said was based on faked material.

Reuters contributed to this report.