A UN rights expert has accused North Korea's regime of turning the country "into one big prison," saying widespread abuses by Pyongyang put it in a class of its own.

In a report due to be examined at the UN Human Rights Council on Monday, the expert, Vitit Muntarbhorn, said the ruling elite had created "a pervasive 'state of fear' or 'state as one big prison'" for the masses.

He called on top UN bodies such as the Security Council and International Criminal Court to play a more active role in tackling the impunity of the state, potentially for crimes against humanity.

"Abuses against the general population for which the authorities should be responsible are both egregious and endemic," the special rapporteur on human rights in North Korea said.

"The human rights situation in this country can be described as 'sui generis' -- in its own category -- given the multiple particularities and anomalies that abound.

"Simply put, there are many instances of human rights violations which are both harrowing and horrific," Muntarbhorn's report said, accusing the military regime of trying "to perpetuate its survival at the cost of the people."

He called on North Korea to immediately restore equitable food distribution, halt executions, physical abuse and violations of civil liberties, and allow him into the country.

North Korea has refused to cooperate with the UN expert. Muntarbhorn has relied on interviews with people who fled to neighbouring countries and information from rights groups and other sources.

"Practices to instil fear among the population are rampant, including public executions, torture, collective punishments and mistreatment of women and children," as well as extensive surveillance, he noted.

He also highlighted reports that the regime had tightened its grip on food distribution by prohibiting smallholders and markets.

"The situation concerning food shortages in 2009 -- with impact on 2010 -- remains severe," especially in the northeast, he added.

Muntarbhorn stressed that "the problem is not simply food shortage but distorted food distribution, from which the elite benefits."