The diplomat sat in the elegant East Side apartments of the Khmer Rouge delegation to the United Nations, examining copies of documents taken from that regime's central prison and interrogation center in Phnom Penh. He pulled out his eyeglasses and asked his translator for help reading the first item.

It was a note written in Khmer to "Deuch," nome de guerre of the prison chief, telling of the confession by torture of the former Khmer Rouge Minister of Information. An underling wrote to Deuch: "He said that he is an idependent CIA officer who buried himself for a long time . . . I have tortured him to write it [the confession] again. With respect . . ."

After reading how one of his closest colleagues had been tortured, the man in the East Side apartments nodded. "Yes, that is true," he said matter-of-factly. "And that is Deuch, head of security." He then verified that the sheet listing his friend's murder appeared authentic. It was entitled, "Prisoners crushed to bits: 6 July 1977." The Information Minister, Hu Nim, was one of 127 victims killed that day, in that way.

Thus Ieng Sry, foreign minister of the exiled Pol Pot regime and long considered its second most important figure, admitted in an interview last week what no other Khmer Rouge leader has acknowledged before -- that it was official policy to liquidate people accused of opposing the regime. These thousands of individuals were among the estimated 2 million Cambodians who persihed under that regime in what is regarded as the worst human horror since the Holocaust.

At the same time, Ieng Sary protested innocence. He claimed he was not among the top leaders who would have known about the purges, though he has been the Khmer Rouge's chief emissary and international spokesman since the communists came to power in 1975. Even after the invading Vietnamese army ousted them in 1979, occupying Cambodia and replacing the Khmer Rouge with Cambodian communists loyal to Hanoi, Ieng Sary has remained foreign minister. He is also the brother-in-law of Pol Pot. When their enemies refer to that regime, it is as the "Pol Pot-Ieng Sary clique."

But Ieng Sary now wants to break that link to Pol Pol and to the regime's crimes, or "mistakes," as he calls them. He insists he was not responsible for the deaths in the prison or elsewhere.

Of the purges, he says: "They told me only that the agents [those accused of being opponents were always convicted of spying for the CIA, the Ietnamese enemy on the KGB] were sent out to cooperatives for re-education,' he maintained through his interpreter. "Personally, I was not aware of the deaths."

His brother-in-law, however, was aware, he said. "Pol Pot maybe did not know the details. He knew the accused were killed -- but not their families." (In a regime with two sisters and their husbands at the top, guilty by blood ties was taken for granted.)

The Khmer Rouge earned infamy when refugees recounted how vast numbers of Cambodians were killed in the countryside. They were bludgeoned to death by axwielding boy soliders who used terror to control the nation. They died of starvation on diets of gruel and cockroaches while the country exported rice to prove it was self-sufficient.

While the Khmer Rouge was in power, Ieng Sary dismissed such refugee stories as so much CIA or Vietnamese propaganda. Later, he and others said upwards of 30,000 Cambodians may have died in the nation that the Khmer Rouge had renamed Democratic Kampuchea. But the Khmer Rouge, he said, was not to blame. The deaths, he said, were the fault of provincial leaders, lower-level bureaucrats who were "agents" of the Vietnamese bent on sabotage.

The refugees, however, did not know of Tuol Sleng, as the prison in Phnom Penh is called today. Few survived the prison to tell their stories. It was only after the Vietnamese invasion that Tuol Sleng came to light. Then Western journalists allowed inside the coutry wrote stories of its torture chambers and its cold-blooded accounting system -- entry sheets, confessions written under torture extermination records -- indicating that nearly 15,000 people were liquidated there.

The victims included foreigners, Cambodian students, doctors and army officers from other Cambodian regimes. The documents show, however, that the great majority were Cambodian communists themselves, political or military figure who either dissented, acted in some manner suggesting dissent, or were linked in some fashion to a dissenter -- by political group, army unit, geography, or, of course, family.

If was documents such as these, photographed by Anthony Barnet at Tuol Sleng and published in London's New Statesmen, that Ieng Sary confirmed as authentic while maintaining his own innocence. "I learned about this in New York," he said. "I knew it [Tuol Sleng] by its number: 21-S. It was headquarters of security. I didn't know the people there were malicious. The lives of the people there were considered like packages, inhuman."

Only two years ago, when I was in Phnom Penh on a trip devoted in part to an alleged investigation of human rights violations in Democratic Kampuchea, Ieng Sary denied a request to see the prisons. He said then: "We have no prisons, no courts. It is people's justice." He laughed at the idea of torture chambers.

But in New York last week, Ieng Sary admitted there was in fact a system of "justice" -- one that included torture chambers and prisons -- and he explained how easy it was for a Khmer Rouge figure to go from office to prison.

"In the beginning [after the 1975 victory], if three people accused someone it was accepted as true," he said. "If three people said someone was an agent of the CIA or KGB, then that person was arrested." Off they went to Tuol Sleng.

Ieng Sary said he knew, for example, that Information Minister Hu Nim had been taken there and that he had "confessed" to being part of an unbelievable conspiracy. He said that at the time he had not seen the report of Hu Nim's death, though it appeared genuine. The country's top three or four leaders at the time, he said, would have known the details of such "security matters." These, he said, were Pol Pot, Defense Minister Son Sen, First Vice Chairman So Phim and National Assembly Minister Noun Chea. Ieng Sary claimed that Noun Chea was the minister with personal responsibility for Tuol Sleng.

Of this group, Pol Pot was the one interested in "reforming" the justice system, Ieng Sary said. To that end, in the first weeks of 1978 Pol Pot required that five people, rather than three, had to accuse for a conviction to hold. Moreover, only activities carried out after 1975 were to be included in the accusations.

Besides the obvious fact that he and his comrades have been ousted from Phnom Penh, Ieng Sary probably admitted what went on in Toul Sleng, and in the regime, because now it is safe and now the evidence is overwhelming. The Vietnamese blitzkrieg in January, 1979, took the Khmer Rouge by surprise. They escaped barely 24 hours before the Vietnamese arrived, leaving behind all their belongings, including the records at Tuol Sleng. Earlier, Ieng Thirth, wife of Ieng Sary, told me what happened.

"We left Phnom Phenh on the 6th of January," she said. "We left all our records there. As I told you, nobody thought we would leave Phnom Penh for good. We left all of our things there, even our clothing."

Leng Thirith also made a plea that her husband not be associated with Pol Pot, her elder sister's husband. "Why do they join Ieng Sary's name with Pol Pot? He was foreign minister, he was always traveling outside the country. Ieng Sary never massacred anybody." She added, tentatively: "Supposing we had committed mass murders, supposing we had committed massacres, Ieng Sary never committed massacres. He was all the time outside the country."

Quite a number of refugees could dispute the claim that Ieng Sary is innocent. But it is safe today for him and for other Khmer Rouge leaders. They are the benefactors of current power struggles in the region, a "necessary evil," in the view of their erstwhile allies. Athough the Khmer Rouge clearly violated the U.N. human rights charter in their barbaric treatment of their own people, they are being encouraged to fight the Vietnamese. For Vietnam, too, broke international law by invading and occupying Cambodia, even though it meant the end of the brutal Khmer Rouge regime.

In this instance, the West, Southeast Asian nations and China have decided to uphold Democratic Kampuchea as representing the legal government of Cambodia. China, with initial encouragement from the United States, provides full support for the Khmer Rouge on the battlefield. Though Western and Southeast Asian nations repeatedly say they don't ever want the Khmer Rouge to return to power, for the moment realpolitik allows the Khmer Rouge to keep their weapons and to sit at the United Nations rather than on trial for their crimes.

It was while he was visiting New York for a special U.N. conference on Cambodia that Ieng Sary gave me the first detailed description of the "justice system" in Democratic Kampuchea. Asked if he ever feared for his own life in such a climate, Ieng Sary replied: "I was accused, myself, of being right wing. . . . Because I was abroad or long times, I was said to be unrealistic, that I was cut off from reality."

Yet, with the exception of his description of the guards at Tuol Sleng, Ieng Sary saw no reason to condemn how justice was carried out. It was the outgrowth of "circumstances," he maintanied.

"Yes, I considered the lives of those people," he said of the prisoners on Tuol Sleng. "But the circumstance was proletarian dictatorship. We were in the middle of class struggle. Under those circumstances . . ."

He did not finish the sentence. Nor did he explain whether "considering the lives of those people" meant he knew they were dead rather than detained in re-education camps.

Finally, I asked if the Cambodian people weren't owned at least an apology rather than the familiar admission of "mistakes," that flat concession that proves to be the worst of a coward's insults. He shook his head: No. "We made mistakes. We want to inform the people of these mistakes so they know we can't have the same policies as we had from 1975 through 1978."

Pressed, he continued: "We apologize when it is premeditated. But who is responsible? I wasn't aware of this [the executions]. How can I apologize? If I had made the instructions to kill . . . No, this is a regime, so we have to change the regime."

Ieng Sary then rushed off to other appointments as the minister of foreign affairs of Democratic Kampuchea, a regime that has changed. Pol Pot is no longer the titular head of state. He only controls the army and the Communist Party.