An international judge attached to Cambodia's Khmer Rouge war crimes tribunal says he has begun investigating a new case of suspected atrocities, without the support of his Cambodian co-investigating judge.

Swiss Judge Laurent Kasper-Ansermet, in a statement Thursday from Phnom Penh, said he does not need the approval of Cambodian colleague You Bunleng to move forward with the new probe. Details of the new case have not been released.

Kasper-Ansermet has the backing of the United Nations in the escalating dispute with the Cambodian government, which has sought to block the jurist from assuming his post and to limit the scope of tribunal investigations.

Kasper-Ansermet was named by the world body to fill the vacancy created when German judge Siegfried Blunk quit the tribunal last year to protest alleged Cambodian interference in judicial matters.

The tribunal has so far convicted former Khmer Rouge prison chief Kaing Guek Eav, better known as Duch. It is currently trying the three most senior surviving members of the regime, who face genocide and other charges in the deaths of up to 2 million people during the regime's 1975-1979 reign.

The Cambodian government includes many former Khmer Rouge members, including Prime Minister Hun Sen. It has voiced strong opposition to pursuing more cases, saying any further prosecutions could divide Cambodian society and spark a civil war. The government also argues that the tribunal's mandate is limited to cases against top Khmer Rouge leaders and those most responsible for atrocities.

For their part, both prosecutors and defense lawyers have for months complained of government interference in judicial matters and accused Cambodian members of the tribunal of failing to pursue other cases against key war crimes suspects.

In October, defense lawyers for defendant Nuon Chea, the number two Khmer Rouge leader, accused the prime minister and several other officials of interfering with their client's right to a fair trial. The lawyers said the interference included unlawfully blocking witnesses from testifying as well as government pressure aimed at preventing new investigations.

The government has denied the accusations.