Rights activists and other Khmer Rouge tribunal experts said Monday the arrests of Ieng Sary and Ieng Thirith were strong indications the tribunal courts would see proceedings through to the end, but they warned the real test will come when actual trials begin.

Former Khmer Rouge in Anlong Veng and Pailin, meanwhile, said the arrest of a man who defected to the government and received royal pardon was unfair, but the former strongholds were quiet.

Document Center of Cambodia Director Youk Chhang called the arrest of "a man of power" thought untouchable by the general public "an important event."

"The Khmer Rouge trial procedure is going forward, with justice and impartiality," said Yoshimatsy Kaori, third secretary to the Embassy of Japan, which contributes the most money to the tribunal. "We welcome all of those who have made the Khmer Rouge tribunal go forward."

Center for Social Development Director Seng Theary said the arrests provided some "renewed hope that the Khmer Rouge tribunal is stepping forward."

However, some experts warned that trials need to start soon if the courts are to be successful.

"The Khmer Rouge tribunal should make it faster, because Cambodians have been waiting for justice for 30 years," said Long Panhavuth, project officer for the independent Open Society Initiative. "But when do we expect the 5th person to be arrested?"

Anlong Veng's deputy mayor and former Tuol Sleng prison photographer, Nhem En, said news of the arrest had not had an effect on the people of the area.

"This is the duty of the national and international court in order to understand the victim issues and [Ieng Sary's] leadership. I have no reaction. I welcome it," he said. "Our people have no reaction to the hundreds of armed police surrounding Ieng Sary's house" and arresting him.

Tuol Sleng survivor Van Nath, 61, said the time he had been waiting for had arrived. "I am increasingly hoping the court is getting near," he said. Former Khmer Rouge cadre Mei Meak, who once acted as a secretary to Pol Pot, said the arrest was of no surprise.

"We are wondering," he said, "if Ieng Sary received amnesty from the former king, and it was he who brought peace in 1996, why was he brought to the [tribunal]?"