WHEN I first met George Pinto Chikoti in 1977, he was a trusted member of the anti-Angolan government guerrilla movement UNITA. Eleven years later, a disillusioned Chikoti left UNITA, revolted, he says, by a long string of human rights abuses within the movement. Those abuses, he charges, came under orders from the group's charismatic leader, Jonas Malheiro Savimbi, a favorite of American conservatives for more than a decade.

Savimbi will tour Capitol Hill this week seeking continuation of the tens of millions of dollars in U.S. aid that he has received since 1986 as well as to renew his close ties with U.S. intelligence officials. Many of those Savimbi will visit are aware of the charges.

Chikoti's allegations against Savimbi include the beating of suspected opponents to death, torture and -- on two occasions -- the mass incineration of adults and children on charges of witchcraft and subversion. Chikoti says Savimbi's targets were precisely those UNITA men and women who seemed most capable of challenging his dominance, then or in the future.

Amnesty International, the human rights group, began reporting on specific allegations in 1988. In two reports issued last year, Amnesty said three women were burned to death in 1982; and it identified Aurora Katalayo, Joao Kalitangui, his wife, three children and a 12-year-old niece among 12 persons burned to death in 1983.

Chikoti says that Aurora Katalayo's 14-year-old daughter, Mbimbi, and 6-year-old son were burned with her. According to Chikoti, Savimbi justified the killing of the children by saying that "The sons and daughters of witches are also witches."

The charges made by Chikoti and other once-trusted defectors of his generation are difficult to dismiss. By going public, they have forever alienated themselves from the man they were taught as children to idolize and exiled themselves from the organization in which they all grew up. Members of their families have denounced them and the lives of their many relatives still in UNITA have been endangered.

UNITA Vice President Jeremias Chitunda, however, rejects all the allegations. In a three-hour interview that I had with four UNITA officials last week, Chitunda called the charges "absolute nonsense." Chitunda was in Washington to prepare for Savimbi's arrival; one of the men with Chitunda, UNITA's United Nations representative Abel Chivukuvuku, is a cousin of Chikoti.

Chitunda said the UNITA defectors fabricated the stories of the killings within UNITA (the group's name in Portuguese stands for the National Union for the Total Independence of Angola). He accused them of being in the pay of the government of the Popular Movement for the Liberation of Angola, which has been supported by the Soviet Union. "What the {Popular Movement} wants is a character assassination campaign against us. It is very well orchestrated. It is very well timed" to correspond to congressional consideration of continued U.S. military support of UNITA.

The Reagan administration resumed covert aid to UNITA through the Central Intelligence Agency in 1986 after Congress repealed a decade-old amendment that had barred U.S. military aid to any of the forces involved. Continued assistance to UNITA was one of the Bush administration's first foreign policy decisions.

Congress will soon vote on the level of military aid to UNITA as part of the 1991 intelligence authorization bill, according to James Gallagher, a policy analyst for the House's Republican Study Committee. The amount of aid is reportedly about $60 million annually. Savimbi is expected to have a round of meetings with members of Congress Monday through Wednesday, Gallagher added.

When George Pinto Chikoti celebrated his 12th birthday in June 1967, Angola was still a Portuguese colony and his father gave the proud boy his first membership card in UNITA with firm instructions to obey the group's leader, Savimbi.

Nine years later, at the outset of the newly independent country's bitter civil war, Chikoti made an overnight transition from English teacher to UNITA guerrilla after fleeing the city of Huambo just ahead of Angolan government troops and their Cuban military allies.

After intense months of guerrilla training in the thick forests of central Angola and a display of mettle in battle, Chikoti was selected by Pedro (Tito) Chingunji for Savimbi's bodyguard detail -- the quickest vehicle to promotion. By then UNITA guerrillas, with the military support of the CIA and the South African Army, had settled into a protracted war with the Popular Movement government.

For me, Chikoti has a special credibility. I first met him in one of Savimbi's main guerrilla bases south of Huambo while on assignment for The Washington Post in early January 1977. By prearrangement with UNITA's former foreign secretary, Jorge Sangumba, I had slipped into Angola across the Zambian border the previous October and, in the course of more than seven months, hiked 2,100 miles through war-ravaged countryside with the guerrillas. I had also visited the UNITA guerrillas in 1973 during their war on the Portuguese for a shorter 800-mile trek.

Fluent in English, Chikoti was assigned for three months to act as my personal bodyguard and interpreter with the Portuguese and Mbundu speakers I interviewed. His primary assignment, however, he told me during a nine-hour interview in mid-September, was to ferret out my impressions and attitudes toward Angola's civil war in general, and about UNITA in particular, and report them back to Savimbi.

While Chikoti and I ultimately became friends during our many days of talking together, Chikoti's first efforts at intelligence gathering were very transparent and he failed to get anything useful from me.

Savimbi attributed Chikoti's failure to his "stupidly becoming the journalist's friend" and Chikoti was punished. He was not allowed to go for South African military training in Namibia in March 1977 with Savimbi's other bodyguards, and instead was sent on a four-month, round-trip hike to the semi-arid Cunene region of southern Angola. In Cunene, Chikoti and other UNITA guerrillas rendezvoused with Portuguese drivers who ferried truckloads of South African-donated, Soviet-made Kalashnikov automatic rifles to UNITA.

Chikoti thought of his punishment at the time as harsh, but in the years that followed he said he learned that his banishment to Cunene was a very mild rebuke compared to the retribution suffered by numbers of UNITA's elite who have incurred Savimbi's wrath. Most of them are dead, Chikoti said, either killed individually or burned alive in groups. The killings in UNITA, Chikoti insists, began in the early 1970s during the clandestine movement's anti-colonial, nine-year war against the Portuguese and escalated under the more strenuous demands of the 15-year-old civil war.

In November 1988, months after George Chikoti left UNITA, others defected when the popular and youthful Tito Chingunji -- who in the intervening years had risen from head of the bodyguard detail to UNITA's foreign secretary -- was recalled from his Washington post back to Angola. Tito, as he prefers to be called, had been an important factor in building UNITA's congressional support. He was, according to several sources, beaten and tortured after being charged with plotting to overthrow Savimbi.

Two other defectors, Sousa Jamba, 24, and Eduardo (Dinho) Chingunji, 26, also literally grew up in UNITA. They have extensive family ties among the small group of interrelated families of educated Angolans who run UNITA.

Jamba's brother, for example, Almerindo Jaka Jamba, 41, is UNITA's secretary of education. Dinho Chingunji is Tito's nephew. His father, the late Samuel Chingunji, was UNITA's first military chief of staff. I hiked into Angola with Samuel Chingunji in 1973, the year before he died under disputed circumstances.

Aurora Katalayo, one of the women Amnesty International said was burned to death in 1983, was Tito's aunt. Her husband, Maj. Mateus Katalayo, was my interpreter during part of 1977. I suspected then that the smart, arrogant, blunt-spoken major would eventually clash with Savimbi. Mateus was much too cynical to deify any man.

UNITA claims the Katalayos were killed in 1982 during combat with Popular Movement government troops. But a person who spoke to Aurora in January 1982 said the angry woman pointedly remarked, "Katalayo is dead!" Aurora was clearly leaving out the normal UNITA expression of "killed in combat," which would have placed her husband on the honor roll of those who died in the movement's cause.

Reached by telephone in London, Sousa Jamba declined to be interviewed because he felt his older brother's life would be endangered. But Dinho Chingunji, who was also reached in London, corroborated Chikoti's tale at many points. Moreover, two persons living in the United States, who have intimate and family ties to UNITA's leadership, corroborated the allegations of the three men. Besides the two mass burnings, Chikoti accuses UNITA leader Savimbi of ordering: The selective and, at times, brutal murders of all intellectuals Savimbi perceives as popular enough within UNITA to challenge his leadership. The beating to death in 1979 of Jonatao and Violetta Chingunji, two elderly UNITA supporters and Tito's parents, after they accused Savimbi of being involved in the death of two of their sons, who were among UNITA's earliest military commanders. One of them, David (Samwimbila) Chingunji, was among the first of 16 UNITA guerrillas trained in China in the mid-'60s. The 1979 beating and imprisonment of the American-educated Jorge Sangumba, UNITA's popular foreign secretary at the outbreak of the civil war, who was seen by Savimbi as a threat to his control of UNITA. Imprisoned in one of UNITA's damp prison pits dug deep into the soil, the rotund and jovial Sangumba is alleged to have dwindled to a thin, haggard and sickly reflection of himself before he died.

In UNITA's detailed written rebuttal to the allegations, there is not one mention of Sangumba. Sangumba and I attended Lincoln University in Pennsylvania in the early 1960s and while I remained neutral to the Angolan civil war, I had grown to like his cutting, brilliant humor.

Pressed several times for details about Sangumba, UNITA vice president Chitunda conceded, "Well, it cannot be said that Sangumba is alive." Sangumba, he said, left in 1984 or 1985, after an extraordinary Congress, to conduct an educational program in central Angola and has not been heard from since. Given Sangumba's stature within UNITA, I found it incredible that Chitunda would not know the date of Sangumba's disappearance. "But," Chitunda insisted, "it is absolute nonsense for anyone to say that he met with foul play. He has never, never been touched!"

At another point, Chitunda warned me that what he considered Angolan government propaganda "is going to drag your name into a kind of lobbyist activity. It is no question that it could do some damage to your professional image, but under no circumstances would I insinuate, 'Leon Dash, please don't write this or that.' "

Chikoti, who lives in exile in Canada, feels American military aid to UNITA should be ended as long as Savimbi continues to lead it. Chikoti nevertheless still believes what his father taught him -- that UNITA represents the legitimate aspirations of his Ovimbundu people, Angola's largest single ethnic group.

"When I talk about human rights abuses, that does not exclude the {Popular Movement government}," said Chikoti. "All of the political movements in Angola have been involved in serious human rights violations.

"But, at the same time, I don't think a dictator like Savimbi, who has ruled UNITA for 25 years, can change. He has to use the {political} system he has created within UNITA to maintain his control. He has killed others who would rule. In a democratic political structure, why couldn't a guy like Sangumba be a leader? Why couldn't a guy like Katalayo be a leader? Why couldn't a person like Tito be a leader? It is impossible because {Savimbi} has killed, beaten or tortured any capable leader who could replace him. These were capable people for me!"

In a democratic organization, Chikoti adds, Savimbi "wouldn't be able to justify his behavior and have people accept what he has said on his relationship with South Africa, on how he killed people within the party. These things are not debated within UNITA!" Perhaps they will be debated in the halls of Congress as Savimbi makes his rounds this week.

Leon Dash, a Washington Post staff reporter, has written extensively about Africa.