A second international judge has resigned from the tribunal prosecuting Khmer Rouge war crimes, complaining of improper interference in his work.

Laurent Kaspar-Ansermet announced his decision Monday, on the same day the tribunal was expecting to hear dramatic evidence from the convicted Khmer Rouge prison warden known as Duch . The Swiss jurist joined the tribunal earlier this year to replace German investigating judge Siegfried Blunt, who had resigned complaining of political interference.

In a formal statement, Kaspar Ansermet said he could not continue because of repeated challenges to his authority by his Cambodian counterpart on the tribunal, You Bunleng. He said he has opened investigations under the tribunal's internal rules dealing with interference in the administration of justice.

The tribunal has already sentenced Kaing Guek Eav, known as Duch, to life in prison, and is currently hearing a second case against the three top surviving Khmer Rouge leaders. However the court is deeply divided whether to proceed with two more prosecutions known as Case 003 and Case 004.

Prime Minister Hun Sen has repeatedly said there should be no further prosecutions after the case now on trial, arguing they would divide and disrupt Cambodian society. Many of the international staff on the court want to proceed, as do many Khmer Rouge victims. But some Cambodians on the U.N.-backed tribunal have sided with the government.

In his statement Monday, Kaspar-Ansermet said You Bunleng has actively opposed investigation into Cases 003 and 004, creating a dysfunctional situation within the court. Most recently, he said, You Bunleng issued an order demanding that the Swiss judge immediately cease what was described as “unlawful activity.”

Karpar-Ansermet noted that the order came in spite of a ruling by the tribunal's pre-trial chamber judges that he had full authority to continue the work of the previous judge, Blunt.

Before his resignation, Blunt himself had been accused of joining You Bunleng in an attempt to shut down Cases 003 and 004 without fully investigating them. Several members of the international staff of the tribunal resigned in protest.