For three years he lived in the silent, nearly empty city of Phnom Penh, reading in his library and eating good food while his shortwave radio told of horrible atrocities in the land just outside his door, where he once was monarch.

Prince Norodom Sihanouk, stunningly guileless for a man steeped in politics, kept his Chinese hosts and foreign journalist visitors dumbstruck for six hours today as he poured out a tale he had kept back too long.

Sihanouk used to delight in his monthly press conferences here during his spell as head of a government-in-exile in the early 1970s. Then he returned to his native Cambodia when the Communists won in 1975 and discovered he had to accept house arrest and silence as the price for the lives of himself and his family.

"I like you very much and I can stay with you three hours, four, five" he said today in the high-pitched, eager-to-please voice that veteran journalists said had not changed since 1975. He dispelled rumors that a stroke had rendered him speechless. "I have had three years of rest, so I can now have some exercise."

After five hours and 49 minutes, the 50 journalists present were exhausted, unable to think of another question, while Sihanouk was still fresh. He insisted on shaking hands with every reporter and kissed some old journalistic acquaintances on the cheek. He could not restrain his delight at returning to the world of letters.

"Are you Art Buchwald?" he asked James Pringle of Newsweek. "I so appreciate Mr. Art Buchwald and you look almost like him."

He said that while he would go on a worldwide mission for the men who had imprisoned him, because he was a patriot, what he really wanted was to leave politics and retire to the French Riviera. He wanted time to ponder in leisure a few new developments he had been unable to research in Phnom Penh, like the nature of the surface of Venus and the style of the new Polish pope.

Two of Sihanouk's daughters and some grandchildren remain somewhere in Cambodia. He was unable to protect them from the draft of workers for the rural cooperatives. But at 56, he indicated he wanted to put his past behind him, do his duty, tell his story and then rest.

For much of his career Sihanouk was a neutralist, trying to keep his small nation clear of the bloody struggle going on between Communist and anticommunist forces in neighboring Vietnam.

Anticommunists in his own army deposed him in early 1970, and his only alternative was to ally with the communists. It was not a comfortable relationship. When the communists won control of Cambodia in 1975, he returned to a country that was being thrown back to a primitive economy, with every part of life strictly regimented, and he didn't like it.

But "to safeguard the life of my family, I had to support" the party's new internal policy, he said. "I might have been killed, and members of my family might have been killed."

Now they have set him free, with his Eurasian wife Monique and their two children, because they need him to win friends abroad.

In the relative safety of Peking, he told this story:

His children by his present wife were allowed for the last three years, to stay with him in the safety of Phnom Penh, but his two daughters by a previous marriage were married and had to accompany their husbands to the countryside.

"I do not exactly know where they are, are they alive, are they dead, are they with the Vietnamese?" he said. President Khieu Samphan "used to tell me they are in good health, but I don't know exactly what their life was like."

"As for Monique, my wife, and the two children, we were very well treated by the Pol Pot regime. We stayed in apartments of the former king of Cambodia. We had very good cooking -- you can see I am very fat -- and we had the right to have a radio. I listened to the VOA in English and Khmer, the BBC, Japan's NHK, everyday."

"I didn't like it that we could not write to our friends, that we could not have Time magazine, or Newsweek, but we were privileged compared to the rest of the nation.

"They may have given us too many privileges, including the privilege not to work, so I read books. I had my library in the royal palace. Lon Nol [the general who deposed him] did not take away my books, so I read in comfort."

Eventually, he said, he proposed that the palace be turned into a national museum so he moved out of it to "a comfortable ensemble of houses, with a very beautiful garden and a small swimming pool, very comfortable, with air conditioning, and I had no complaint.

"I know that the radios talk and talk about violations of human rights in Cambodia. I know that President Jimmy Carter said the Cambodian regime is the worst violator of human rights in the world."

But, Sihanouk said, "I did not see any killings... I hope that the horrible things that they say happened did not happen in Cambodia."

Five or six times, he said, Khieu Samphan, on Pol Pot's orders, took Sihanouk on trips into the countryside where he was able to observe the people.

"They work very hard, but they are not unhappy," he said. "On the contrary, they smile. On their lips we could hear songs, revolutionary songs naturally, not love songs. I prefer love songs. I was a crooner, I composed many love songs, but the new revolutionary songs are not so bad.

"And the children, they played. They had no toys but they could run, they could laugh.They could eat bananas, which they had in the gardens of the cooperatives, and the food of the cooperatives was not bad, naturally not as good as my food in Phnom Penh, but good... They are not fat like me, but they are not skinny."

But back in Phnom Penh, he could see no one, not even Teng Ying-chao, the widow of his good friend, Chinese Premier Chou En-lai, when she came on a state visit.

What really hurt him, he said, was the death of Chairman Mao. When he arrived here Saturday, "Chinese friends said to me, 'A great part of the Chinese people were not happy when you kept quiet at the death of the great Chairman Mao. You were here five years and we helped you a lot, and he died and you did not send any condolence to us.'

"You know, I have to tell you the truth about it. Immediately when we knew, after listening to the Chinese radio, we wept. My wife and I wept because Chairman Mao was for us more than a father," Sihanouk said as, in front of the crowd in the Great Hall of the People, he put a hand in front of his face and sobbed.

"I sent off letter after letter, five letters to my government to have the permission to pay my humble respects to Chairman Mao Tse-tung. I am a humble citizen. May I secretly be able to make condolences to the Chinese Embassy at night, or to send a little letter to Madame Mao Tse-tung, Chiang Ching, just in private? It is not necessary to make public such things. I got no answer."

Sihanouk seemed unaware that no one in China refers to Chiang Ching, purged from power a month after Mao's death, with such respect any more, and certainly not in the Great Hall.

Suddenly, last Friday, after he had listened to the evening VOA news, Sihanouk-said, "a black Mercedes entered my compound. It was Khieu Samphan. He said, 'Pol Pot wants to see you.' Pol Pot was waiting for me in the great hall of the government palace, much smiling. He shakes hands with much friendship. We embrace each other.

"He presented to me our military situation. He said we are in great difficulty... 'It's time for you to help us in the diplomatic field, since you are very popluar with the press,'" Sihanouk, giggling, quoted Pol Pot as saying, "'and very popular in the United Nations. Do you want to help us?' I told him I was ready."

When this campaign is over, Sihanouk said, "as far as I myself am concerned, I am disgusted with the political life. I do not want to be involved again in the government affairs of my country, but as a citizen and a patriot, I will speak out against the Vietnamese aggressors.

"I will ask permission to go to France to live the rest of my life, because I have a small residence" on the Riviera.