SEOUL (REUTERS) - A United Nations (UN) panel will start hearing harrowing testimony from North Korean defectors on Tuesday in a move that will likely mobilise public opinion on abuses in the one-party state that comes at or near the bottom of most measures of freedom.

There are an estimated 150,000-200,000 people in North Korean prison camps, according to independent estimates, and defectors say many inmates are malnourished or worked to death.

The panel will gather evidence in the South Korean capital, Seoul, this week and then move to Tokyo to tackle the issue of abductions of Japanese citizens.

North Korea's best-known defector, Shin Dong Hyuk, and Kim Hye Sook, another political prison camp survivor, are expected to testify publicly about hardships endured and executions witnessed during their decades of captivity, they said.

Mr Shin told Reuters in June he would bear witness to the horrors of his life in a prison known as Camp 14 to help build an eventual criminal case against North Korea's leadership.

"This is something I should do, let the whole world know the situation in order to help get rid of those camps," said Mr Shin, 30, the only defector known to have been born in a prison camp and who escaped.

This is the first time that the North's human rights record has been examined by an expert panel, although Pyongyang, now ruled by a third generation of the founding Kim family, denies that it abuses human rights.

North Korea has denied access to investigators and few experts expect the commission to have an immediate impact on the rights situation there, although it will serve to publicise a campaign that has little visibility globally.

"The UN has tried various ways to pressure North Korea over the years in the field of human rights, and this is a way to raise the pressure a bit," said Mr Bill Schabas, professor of international law at Middlesex University in Britain.

"But it's obvious that North Korea is a tough nut to crack and the UN's means are limited. There would need to be profound political changes in North Korea to make headway in the field of human rights."

THIRD KIM CLEAVES TO FATHER'S LINE

After more than a year and a half ruling North Korea, 30-year old leader Kim Jong Un has shown few signs of changing the rigid rule of his father and grandfather. Neither have there been signs of a thaw or loss of control inside the tightly controlled state.

Mr Kim stepped up his father's nuclear weapons and rocket programmes with a third nuclear test and two rocket launches and has repeatedly emphasised the military in his speeches.

This year, he threatened the United States (US), South Korea and Japan with nuclear attack and although the country's bellicose moves were dismissed as empty rhetoric, Mr Kim succeeded in driving tension on the divided Korean peninsula sharply higher.

The hope of many activists would be for the Kim dynasty to fall and for leaders in Pyongyang to be put on trial at the International Criminal Court (ICC) in the Hague, although the UN commission of inquiry (COI) says this is not an option at present.

"At this stage, it is not appropriate for the COI to comment on whether or how the ICC's jurisdiction over potential crimes against humanity could be established," the commission said, adding that North Korea had not signed the statutes that would allow it to be prosecuted in the Hague court.

"It is better than nothing," Mr Lee Min Bok, a defector and Christian missionary who has sent millions of anti-Kim leaflets into the North using helium balloons since 2003, said of the commission.

"It is not going to work unless the regime is changed."