Top officials of the Church of Jesus Christ of Latter-day Saints say they are investigating reports from members that, as children, they witnessed human sacrifices and suffered ''satanic abuse'' at the hands of renegade Mormon-affiliated cliques.

Glenn L. Pace, a member of the church`s three-man presiding bishopric, reported in a memorandum dated July 19, 1990, and made public last week that an internal church investigation detailed 60 cases in which Mormons described undergoing ritualized abuse in Utah, Idaho, California, Mexico and other locations.

Pace wrote that he is personally convinced at least 800 church-affiliated Satanists now are practicing occult rituals and devil worship in the Salt Lake Valley.

Many of them, he added, pose as devout Mormon leaders and include bishops, a diocese president, patriarchs, temple workers, members of the church`s Young Women and Young Men groups, and even members of the world famous Mormon Tabernacle Choir.

''Not only do some of the perpetrators represent a cross section of the Mormon culture, but sometimes the abuse has taken place in our own

meetinghouses,'' Pace wrote to the committee set up by patriarchs to investigate behavior that weakens the 8-million-member church.

However, Pace wrote, he made a point of asking the victims to identify their tormentors only by their church rank. He gave no reason for this.

Church spokesman Don LeFevre said he did not know if Pace reported his findings to law-enforcement officers.

Pace, he added, is traveling in South America and is not available for interviews.

LeFevre noted that many law-enforcement officials have expressed skepticism about Pace`s allegations of widespread satanic abuse. He appeared to share that view.

''It seems to me that even though one actual case is tragic and is one too many, the reports of ritualistic killings are likely overblown, whether they be in connection with members of our church, of other churches or any other segment of society, none of which is immune,'' LeFevre said.

Sgt. Don Bell, chief of the Salt Lake City police department`s intelligence unit, said his office receives about a half-dozen reports alleging satanic abuse each year. But there are no reports of finding the body of a sacrifice victim.

''I have no doubt whatsoever that these people who describe enduring satanic ritual abuse are victims of some very profound type of abuse,'' Bell said. ''But I do not believe that there is an inter-generational network of Satanists active in this valley.

''In 20 years of doing law-enforcement work in this city I am unaware of any case where we had some sort of cult and part of the ritual was to sacrifice children, conduct human sacrifices, drink human blood or any of those bizarre things.

''On the other hand, I can cite case after case where we have contact with mental health care professionals who have a patient who tells them that they witnessed a sacrificial killing or something and have convinced the psychologist or whatever that it really did happen.''

Pace`s memo, marked ''Do Not Reproduce'' at the top, was made public last week by anti-Mormon crusaders Jerald and Sandra Tanner, who also played a key role in publicizing the so-called ''White Salamander Letter.''

The letter, which Jerald Tanner exposed as a forgery, made it appear that church founder Joseph Smith had been involved in folk magic and satanic rites in the early 1800s when he wrote the Book of Mormon.

Mark Hofmann, who had forged the letter and sold it to church elders, is now an inmate at the Utah State Prison. Two people were killed in pipe bomb attacks mounted by Hofmann.

Of the Pace memo, Sandra Tanner said last week: ''We do not know that these tales of satanic rituals and human sacrifices are true.

''But we do know than Pace is a very high ranking church official, and we know that the memo in question is authentic and therefore of great interest to all people concerned about Mormonism, both those inside the church and those on the outside.''

Pace had written he also was skeptical of the allegations until he spent a year interviewing survivors of the rituals, many of whom suffer multiple personalities and other psychological problems commonly associated with child abuse.

''When 60 witnesses testify to the same type of torture and murder, it becomes impossible for me, personally, not to believe them,'' the bishop wrote.

The Satanists` ceremonies often are based loosely upon the Mormon church`s own rituals, Pace wrote.

''For example, the (Mormon church) verbiage and gestures are used in a

(satanic) ritualistic ceremony in a very debased and often bloody manner,''

he wrote. ''When the victim goes to the temple and hears the exact words, horrible memories are triggered.

''The memories seem to come in layers. For example, the first memory might be of incest; then they remember robes and candles; next they realize that their father or mother or both were present when they were being abused. ''Another layer will be the memory of seeing other people hurt and even killed. Then they remember having seen babies killed.

''Another layer is realizing that they participated in the sacrifices. One of the most painful memories may be that they even sacrificed their own baby . . . ''

The church`s ruling three-man First Presidency led by Ezra Taft Benson, Mormonism`s ruling patriarch, sent a letter to local church leaders Sept. 22 warning about Satanism.

''We express our love and concern to innocent victims who have been subjected to these practices by conspiring men and women,'' the letter said.

It warned all church members ''not to affiliate in any way with the occult or those mysterious powers it espouses,'' and concluded: ''These things should not be pursued as games, be topics in church meetings, or be delved into in private, personal conversations.''