Cambodian interpreters angry that they have gone without pay for three months have stopped working at the genocide trial of former Khmer Rouge leaders in Phnom Penh, Cambodia.

In a setback for international justice, 30 Cambodian translation staff members assigned to the U.N. backed trial and who have gone without pay since December, have announced they are going on strike.

The announcement came just before the court was to hear testimony from a foreign expert, according to Khmer Rouge tribunal spokesman Neth Pheaktra. “This morning’s hearing is temporarily delayed so judges can meet with administration staff to talk about pay,” said Pheaktra.

Testimony that had been scheduled to be given this week and next has been postponed until the dispute can be resolved.

The 30 striking interpreters have offered to return to work if they receive their December paychecks but will walk out again at the end of the month unless they have a new contract. The interpreters’ old contract expired in January.

Trial Chamber President Nil Nonn said the strike has affected the translation of documents as well as court proceedings.

Local staff at the tribunal has been without pay since December because countries that agreed to fund the court have no timeline for sending in their contributions. The court is still waiting for $300,000 the European Union pledged for 2012.

The Khmer Rouge Tribunal was established as part of a joint agreement between the Cambodian government and the United Nations to try leaders of the Khmer Rouge for war crimes and crimes against humanity.