The first public hearing of a Khmer Rouge leader, held this week, should silence critics of the government's efforts for a tribunal, a spokesman said Friday.

The hearing, on whether prison chief Duch should be released ahead of atrocity trials, brought hundreds of journalists and observers and was carried on television.

"This is like ice water being splashed on the face of those cursing the government [efforts] so far," spokesman Khieu Kanharith said.

But tribunal observers have warned that the hearing was only one step on a long road fraught with pitfalls.

"What has been achieved so far is just a step forward. It is a long journey to complete," opposition leader Sam Rainsy said.

"The tribunal is gradually working its ways to its independence," said Youk Chhang, director of the Documentation Center of Cambodia. "This is what we are going to stick to in order to achieve justice."