Media playback is unsupported on your device Media caption Michael Kirby: "They had to live on rodents, grasshoppers, lizards and grass"

A UN rights investigation into North Korea has shown there is evidence of widespread violations by the state.

Those who survived North Korean prisons suffered "unspeakable atrocities", said the UN panel, who interviewed exiles and former prisoners.

A North Korean official in Geneva, where the findings were presented on Tuesday, denied the findings.

The North is frequently accused of rights violations, including torture, abductions and running prison camps.

The UN panel members of this landmark investigation into North Korea interviewed witnesses in Seoul, South Korea, and Tokyo, Japan, last month.

The panel was set up to investigate "the systematic, widespread and grave violations of human rights" in North Korea, the UN said in a previous statement.

Image caption North Korea has refused requests from the UN panel to enter the country

Michael Kirby, who headed the inquiry, told the UN Human Rights Council on Tuesday that the witness testimonies were not isolated cases.

"They are representative of large-scale patterns that may constitute systematic and gross human rights violations," he said as part of the panel's preliminary report.

He added the testimonies gave "a face and voice to great human suffering".

Some of the atrocities reported included a woman forced to drown her own baby; children imprisoned from birth and starved; and families tortured for watching a foreign soap opera.

Mr Kirby told BBC World TV that they had received testimony from people who had been born into the prison camps because their family members were already there.

"They had to live on rodents, grasshoppers, lizards and on grass and they were subject to cruelty," he said.

Mr Kirby said that one case told of inmates having to watch the public execution of their mother and brother.

He added: "All in all it is a very horrifying story, the like of which I don't think I've seen or read of since the Khmer Rouge [in Cambodia] and the Nazi atrocities during the second world war."

The panel have yet to determine those responsible for the violations.

North Korea, however, has dismissed the report as part of a defamatory campaign aimed at regime change. It has not co-operated with the investigation and denies the existence of prison camps.

North Korean ambassador, So Se-pyong, told the council that the evidence was "fabricated and invented by forces hostile" to the country.

UN investigators have repeatedly asked Pyongyang to let them into the country, but their requests have been refused so far.

The final UN report is not due until March next year.