Mao Zedong's Cultural Revolution was an eruption of ideological fervor, mass hysteria and outright brutality that left an estimated 10 million Chinese dead and ruined the lives of millions more. Now tales of even more horrible excesses from the years between 1966 and 1976 are coming to light: allegations of cannibalism, involving hundreds of men and women who violated mankind's most powerful taboo in the name of revolutionary purity.

Evidence that cannibalism was not only practiced but condoned and even encouraged by some Communist Party officials emerged last week with the arrival in the U.S. of Zheng Yi, a dissident novelist who has been on Beijing's most wanted list since the 1989 Tiananmen Square massacre. Zheng, now 45, spent three years hiding in China before escaping to Hong Kong nine months ago. On the run as a fugitive, he managed to recover a number of the secret government reports that he had collected over the years. He used them to document two books, which he and his wife eventually smuggled out of the country.

Prepared in the mid-1980s and suppressed by the authorities, the documents reveal that cannibalism was widely practiced in the late '60s in the Guangxi Autonomous Region in southern China. Acting without the sanction of national party authorities, the documents reveal, several party leaders in Guangxi incited followers to kill "class enemies" and then eat their flesh in public ceremonies. Zheng also conducted his own extensive investigation into the reports of cannibalism. He says he interviewed relatives of victims and spoke with dozens of people who confessed to having eaten human flesh. He insists that his case is persuasive.

There is no evidence that Mao Zedong knew cannibalism was being practiced during the Cultural Revolution. When Premier Zhou Enlai heard about the crimes in Guangxi, he ordered party officials to put a stop to them. Nonetheless, according to Zheng, amid the anarchy of the times cannibalism apparently persisted in Guangxi. "I believe Zheng's story," says Perry Link, a professor of Chinese at Princeton. "He's a writer of integrity, and the rich detail has the ring of authenticity." Chinese officials now disclaim any knowledge of the practice. Said a Public Security official in Beijing: "I've never heard of this."

The atrocities took many forms, according to documents. One report refers to "eating people as an after-dinner snack . . .barbecuing people's livers . . .banqueting on human meat." The same document matter-of-factly relates specific tales of depravity. "On May 14, 1968," it says, "a group of 11, led by the Wei brothers, captured a man named Chen Guorong and killed him with a big knife before cutting out his liver. They shared the human meat with 20 participants." The same month Wu Shufang, a teacher at the Wuxuan Middle School, was beaten to death; her liver was roasted and eaten. During 1968, 91 members of the Communist Party in Guangxi were expelled on charges that they were involved in cannibalism, but none was severely punished.

Rumors about cannibalistic practices began to surface shortly after the atrocities occurred, but they were squelched by the authorities. Zheng heard the first stories in 1968, when he was a Red Guard in Guilin, in northeastern Guangxi. He was skeptical, but 16 years later, established as a novelist, he asked Liu Binyan, a dissident journalist who now lives in the U.S., if the stories might be true. "Liu told me they were," Zheng recalls, "but he had not wanted to write about them because the subject was so nasty."

The exchange spurred Zheng to try to bring the sordid story to light. Visiting the county of Shanglin, north of Nanning, Zheng found that cannibalism was openly discussed years after the fact. An old man named Yi Wansheng told Zheng, "Yes, I confess everything," and proceeded to describe how he had killed one victim, a landlord's son. "I used a knife to cut him. The first knife was dull, so I threw it away. With another knife I was able to open his chest. But when I tried to pull out his heart and liver, the blood was too hot for my hand and I had to bring some water to cool it. When I took the organs out, I cut them to pieces and shared them with the people of the village."

In the two decades since the end of the Cultural Revolution, most of the great upheaval's excesses have been publicized as part of senior leader Deng Xiaoping's campaign to discredit Maoist orthodoxy. Why have the stories of cannibalism remained under wraps? "Many of the people involved are still in power in Guangxi," Zheng suggests. "Some of those people told me to beware or I might get myself killed." Equally important, he feels, any revelation of the atrocities would be profoundly embarrassing to the Beijing government. "Top leadership has known about it all along," Zheng charges, "but it has not wanted anyone else to know."