Condemning the repression and mismanagement by what he called North's "cloistered, controlled and callous" power base, he said the situation of many North Koreans facing food shortages had become desperate.
"It is the exploitation of the ordinary people which has become the pernicious prerogative of the ruling elite," Muntarbhorn said, adding that he estimated about a third of the North's 24 million people were hungry.
"While many members of the population are in abject poverty and suffer the prolonged deprivations linked with shortage of food and other necessities, the country itself is endowed with vast mineral resources controlled by the authorities."
He said the situation was all the more ironic since North Korea's economy was reported to have improved slightly over the past year, indicating that more resources could be available.
|The report said up to one-third of North Koreans are hungry [GALLO/GETTY]
But instead Muntarbhorn said the money was being misspent on the "military first" policy – known as "Songun" – that is emphasised in North Korea's constitution.
In a scathing report, he called on the North's rulers to dismantle the country's pervasive surveillance system, develop an independent judiciary, and instituting checks and balances against the abuse of power.
"The freedoms from want, from fear, from discrimination, from persecution and from exploitation are regrettably transgressed with impunity by those authorities, in an astonishing setting of abuse after abuse."
He said North Koreans lived in a society where persecution, clampdowns, collective punishment, torture, arbitrary executions and public executions were the norm.
"The pervasive repression imposed by the authorities ensures that the people live in continual fear"
UN Special Rapporteur for North Korea
"The pervasive repression imposed by the authorities ensures that the people live in continual fear," he said.
Muntarbhorn, a Thai professor, has investigated North Korea's rights situation for nearly six years but never been allowed entry to the secretive and virtually closed-off country.
His report was based on consultations with other UN agencies working in the country, human rights groups and other experts as well as first hand reports from North Korean refugees in South Korea, Japan and Mongolia.
Responding to the report, North Korea's deputy ambassador the UN, condemned the findings saying it was "full of distortion, lies and falsity."
Pak Tok Hun said the report had been "politically conspired" by hostile forces and said that pressuring the country over the issue was "totally useless and will rather intensify the pride in our human rights protection system."
North Korea, he said, was especially proud of its free health and education.
In a separate development on Friday, a spokesman for South Korea's president declined comment on reports of a secret meeting in Singapore last week between officials from North and South Korea.
According to South Korea's KBS television network, the meeting was held to discuss a possible summit of their leaders.
Citing an unidentified source, KBS said the talks ended without agreement after the North rejected South Korean demands that the summit be held in Seoul, citing concern for the security of the North Korean leader, Kim Jong-il.
The leaders of North and South Korea have only ever held two summit meetings of their leaders, one in 2000 and a second in 2007.
On both occasions the summit was held in the North Korean capital, Pyongyang.
Asked to confirm the reported meeting in Singapore, an official at the South's presidential Blue House said: "I have nothing to say."