The United Nations has said it is disturbed about the resignation of Laurent Kasper-Ansermet from the UN-backed Khmer Rouge war crimes tribunal in Cambodia.

The Swiss reserve co-investigating judge on March 19 cited political interference by the country’s government after he tried to investigate more suspects and their roles in the revolution that killed as many as 2.2 million Cambodians between 1975 and 1979.

His German predecessor, Siegfried Blunk, quit for similar reasons in October.

“[The UN] is very concerned by this alarming development,” said Martin Nesirky, spokesman for UN Secretary-General Ban Ki-moon.

Kasper-Ansermet, who took over in November and will resign on May 4, said he had been constantly undermined by his Cambodian counterpart, You Bunleng.

Kasper-Ansermet's resignation is the latest setback for a court that has spent more than $150 million (SFr138 million) since its creation in 2005, passing just one sentence. Kaing Guek Eav, also known as Duch, was given a 35-year jail term, commuted to 19 years, for his role in the deaths of more than 14,000 people at a torture centre.

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