Judges investigating the murderous Khmer Rouge regime joined other court officials for the three-day visit to the western, Pailin region to "meet and talk" with former rebels, said tribunal spokesman Reach Sambath.
"The aim of the meetings is to explain to them about the role of tribunal and its mandate -- that this court will only try the most senior and the most responsible Khmer Rouge leaders, and the ordinary Khmer Rouge officials should not be worried," he told AFP.
The visit also aimed to clear up misunderstandings about the joint Cambodian-UN tribunal in the hope of convincing many to give evidence for the prosecution in upcoming trials, Reach Sambath said.
"We need cooperation from many of them because they could be key witnesses in order to assist the trials," he said.
Pailin, near the Thai border, was one of the final refuges of the brutal regime which was driven out of power in 1979, and many soldiers and officials fled to the remote region to regroup and try and battle the new government.
Up to two million people died of starvation, overwork or were executed under the Khmer Rouge, which emptied Cambodia's cities, exiling millions to vast collective farms in a bid to forge an agrarian utopia.
The tribunal, established in July 2006 after nearly a decade of negotiations between Cambodia and the United Nations, seeks to prosecute crimes committed by senior Khmer Rouge leaders.
Five heads have been detained to face charges for crimes committed during the regime's 1975-79 rule. Trials are expected to begin in mid-2008.
All the defendants claim to be suffering from serious health ailments, causing concern among those hoping to find justice before the alleged perpetrators die.