UN urges Cambodia not to meddle

The United Nations has 'strongly urged' the Cambodian government not to meddle in the work of a UN-backed Khmer Rouge court after a judge quit, citing political opposition to two new cases.

'The Legal Counsel strongly urged the royal government of Cambodia to refrain from statements opposing the progress of cases 003 and 004 and to refrain from interfering in any way whatsoever with the judicial process,' said UN under-secretary general for legal affairs Patricia O'Brien in a statement on Thursday.

The high-ranking UN official was speaking after meeting Cambodian Deputy Prime Minister Sok An in the capital, Phnom Penh, amid mounting concern over political pressure on the tribunal.

German judge Siegfried Blunk resigned on October 9 claiming repeated government statements opposing two possible new cases linked to the 1975-1979 Khmer Rouge regime effectively made his position untenable.

The shock departure of Blunk, one of two judges responsible for issuing indictments, has rocked the court and prompted observers to call for UN action against long-standing allegations of government meddling.

Phnom Penh has strongly denied interfering but Prime Minister Hun Sen - himself a former cadre - has made it clear he wants the court's work to end with the current second trial, even saying further cases were 'not allowed'.

Court monitor Randle DeFalco, a legal adviser to the Documentation Centre of Cambodia, which researches Khmer Rouge atrocities, cautiously welcomed O'Brien's comments, the UN's strongest reaction yet to the court controversy.

'It's a step in the right direction,' he said.

'But an inquiry still appears necessary to restore public confidence in the court,' he added, noting that Blunk's resignation raised questions over whether the court's investigating office has been properly carrying out its duties.

In a media release after the meeting with O'Brien, the government said both parties had 'reiterated their strong support' for the Khmer Rouge tribunal, which has cost more than $US100 million ($A98 million).

Sok An also urged both sides not 'to be distracted by intense speculation, pressure and interference from the media and other outside parties', it said.

The tribunal's controversial third and fourth cases involve five ex-regime members who are accused of an array of crimes, including mass killings and forced labour.

Their cases are officially still under consideration but critics said Blunk and his Cambodian counterpart were failing to investigate them fully in the face of government objections and they were widely expected to be dismissed.

The court, made up of Cambodian and international legal officials, was set up in 2006 to provide some justice for the nation traumatised by the deaths of up to two million people under the communist movement's reign of terror.

It has so far completed just one trial - jailing Kaing Guek Eav, a former Khmer Rouge prison chief, last year for 30 years for overseeing the deaths of some 15,000 people. The case is now under appeal.

A second trial involving the regime's four most senior surviving leaders - including Brother Number Two' Nuon Chea - is expected to start hearing testimony next month.

A lawyer for one of the accused in that case, ex-social affairs minister Ieng Thirith, told the court on Thursday her client suffers from dementia and should not have to face trial.

Judges are expected to rule on the elderly woman's mental fitness in the coming weeks.

Led by Brother Number One' Pol Pot, who died in 1998, the Khmer Rouge wiped out nearly a quarter of the population through starvation, overwork or execution in a bid to create an agrarian utopia.