The documents, which arrived in 26 boxes from the Swedish government Monday, had been kept in the European country for the past three decades, said Youk Chhang, director of the Documentation Center of Cambodia.
“They are historically important. It will be very useful for the prosecutors as well,” he said.
The director, who is a survivor of the ultra-Maoist regime of the 1970s, said he had learned about the documents’ existence during a trip to Sweden in 2000 and asked the Swedish government to hand them over.
“I am still reading through them all,” Youk Chhang said, adding the documents were written in English, French, Swedish and Khmer.
The director said he had yet to learn the exact contents of the documents and why they were in Sweden, adding he would hand over the materials to the UN-backed Khmer Rouge tribunal.
Cambodian and international jurists were sworn in last year to the long-delayed tribunal, which will try surviving leaders of the regime.
Prosecutors have begun building cases against possible defendants, but the first trials are still months away.
Proceedings have been held up by disagreement among Cambodian and foreign jurists over internal rules that will give shape to the trials.
Up to two million people died of starvation, overwork and from execution during the 1975-79 rule of the communist Khmer Rouge, which abolished religion, property rights, currency and schools.
Khmer Rouge leader Pol Pot died in 1998, and so far only one potential defendant is in custody.
The slow pace of bringing other aging former cadres to trial has heightened fears that they could die before facing justice.