New Zealand taxpayers are contributing a further $200,000 towards the Cambodian War Crimes Tribunal.
The United Nations-backed tribunal was set up in 2006 to try senior members of the Khmer Rouge regime for genocide and crimes against humanity after up to two million people were killed between 1975 and 1979.
New Zealanders have previously donated $1.2 million since 2006, but Prime Minister John Key says the court is under significant financial pressure.
Mr Key says he hopes donors from around the world will follow suit.
While in Cambodia for the East Asia Summit, Mr Key will visit the court to meet one of its five judges, the former Governor-General Dame Silvia Cartwright.
The tribunal is considering the crimes committed by individuals in the Khmer Rouge government, which was responsible for the deaths of as many as two million Cambodians between 1975 and 1979.
