SEOUL (REUTERS) - After a year of investigation, the United Nations is set to release a detailed report on human rights violations in North Korea, but defectors from the country and experts are deeply sceptical it will have any effect on the regime in Pyongyang.

The UN Commission of Inquiry on human rights in North Korea was set up last March to begin building a case for possible criminal prosecution.

Mr Michael Kirby, a former chief justice of Australia who chairs the independent inquiry, said after preliminary findings last year that inmates in North Korea's prison camps suffered "unspeakable atrocities", comparable with Nazi abuses uncovered after World War 2.

But any attempt to follow up after the final report is issued on Monday will most likely be blocked by China. North Korea itself labels any attack on its human rights record as a US-led conspiracy.

China, the North's major ally and main benefactor, stands ready to veto any attempt to mobilise the Security Council to open an investigation against Pyongyang, a non-signatory to the International Criminal Court.

"In some respects I have been disappointed with the United Nations, although the UN is trying to resolve the issue" said Shin Dong Hyuk, a North Korean defector who has given the UN panel 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".

"The Human Rights Council, the biggest organisation in the UN, has not solved any problems," Mr Shin said in an interview in Seoul ahead of the report's release.

In March 2013, the Council established the Commission of Inquiry to investigate violations of human rights in North Korea and to seek out those accountable, "in particular where the violations may amount to crimes against humanity." More than 200,000 people are believed to be held in North Korean prison camps, according to independent estimates.

The UN panel has worked to bring new attention to the allegations of horror at North Korea's gulags with evidence and testimony from exiles, including camp survivors, in Seoul, Tokyo, London and Washington but has failed to gain access to North Korea.

Mr Shin said China continues to use North Korea as a tool to keep US influence in the region under control.

"So far China has neglected North Korea's human rights issue and supported its dictatorship," said Mr Shin, who is scheduled to address the UN Human Rights Council in March when the panel's findings are formally presented.

After more than two years in power, North Korean leader Kim Jong Un shows no signs of changing the iron-fisted rule of his predecessors, forging ahead with a reign of terror and ordering the execution of his powerful uncle following a brutal public purge.

"North Korea won't bat an eyelid," said Hwang Jae Ok, vice president of the Institute for Peace and Cooperation in Seoul, who has extensively studied Pyongyang's human rights record. "It has built up a strong tolerance to sanctions and pressure."

The North has been under gradually tougher international and US sanctions since its first nuclear test in 2006.

The sanctions have not stopped Mr Kim, believed to be in his early 30s, from stepping up the nuclear and missile programmes launched by his father and accomplishing what experts have said were notable successes that have turned the clock back on years of disarmament efforts led by Washington.

Human rights activists hope the panel's report work and the global attention it generates will seep back across North Korea.

But Baek Kyung Yoon, a North Korean female army captain who fled to the South in 2000, said her former compatriots are unlikely to have the luxury of pondering about human rights or anticipating improvement.

"Loyalty (to the regime) is everything and it's nonsense to discuss human rights there," Ms Baek said on Wednesday, ahead of the premiere of "The Apostle: He Was Anointed By God". The Korean-language film is based on her experience of ordering the torture of a man who possessed a few pages from the Bible.

A US Christian missionary, Kenneth Bae, was sentenced last year to 15 years of hard labour after being convicted of state subversion. Pyongyang has abruptly rescinded a visit by US special envoy to seek Bae's release for a second time.

Religious persecution is one of 11 areas of inquiry by the UN panel, which also include food deprivation, torture, executions and abductions.

Despite his frustration with the lack of visible progress, Mr Shin, who had a finger chopped off with a butcher knife by prison guards as a punishment, still hopes the United Nations can bring change in North Korea.

"Personally the COI (Commission of Inquiry) is my last remaining hope. Even if there is little chance for change, I am betting everything I have."