FBI Director J. Edgar Hoover withheld evidence from Justice Department prosecutors about a 1963 church bombing case in Birmingham that killed four black children.

Sources familiar with a Justice Department report on the activities of Ku Klux Klan informant Gary Thomas Rowe said documents in FBI files show Hoover rejected recommendations from his Birmingham field office that testimony identifying suspects in the bombing be forwarded to civil rights division prosecutors for a legal opinion.

Melton Alexander, the FBI agent in Birmingham who questioned witness placing the suspects at the bombing scene, said in a phone interview from Birmingham yesterday that his request to brief the local U.S. attorney and state prosecutor also was turned down.

"I'm not saying the case was prosecutable then, but I thought someone in the prosecutive arm should take a good solid look at it," said Alexander, who is now chief of the criminal division in the U.S. attorney's office in Birmingham.

"You can't fault the effort on that case. We had 100 agents working on it at one time," he added.

Sources said the Justice report quoted Hoover memos as turning down Alexander's requests because he felt the chances for successful prosecution were "very remote." The first disclosure of the report's results were published in yesterday's editions of The New York Times.

Justice and FBI officials contacted yesterday said they were puzzled why Hoover refused to turn over the information. "It was the kind of glory-grabbing case he would have wanted to be in on," said one.

John Doar and Burke Marshall, the top civil rights attorneys in the Justice Department at the time, said in phone interviews yesterday that FBI headquarters never informed them there was a breakthrough in the case, which generated nationwide publicity at the time.

"I'm stunned," Marshall said. "It's conceivable that Hoover was right (that the evidence wasn't strong enough) but that should have been left up to us, the prosecutors."

Doar said he recalled that there were jurisdictional problems in the investigation because of a lack of federal statutes that applied. "But I never heard of the rule that said J. Edgar Hoover decided what was a case," he said. And they [FBI officials] were trying to develop prosecutable cases at the time in other instances of racial violence in the South."

R. Macey Taylor, assistant U.S. attorney in charge of such cases in Birmingham at the time, said he too never received the FBI evidence about the September 1963 bombing of the 16th Street Baptist Church. "The evidence might well have been marginal. But at least we would have presented it to a grand jury," he said.

It was not until 1977 that one of the suspected Klansmen, Robert E. Chambliss, was convicted on a state murder charge in the case.

The Justice report on the activities of Klan informant Rowe has been "under review" at Justice for several months, according to Paul R. Michel, the acting deputy attorney general.

He said department officials have been working on a summary of the 300-page report to be sent to Congress. Some members requested the study after news reports in 1978 that Rowe took part in the race violence while on the FBI payroll in the 1960s.

Rowe is now facing murder charges in Alabama for the 1965 death of Viola Gregg Liuzoo, a white civil rights worker from Detroit. Michel said the department decided that releasing the Rowe Task Force report might prejudice the trail.

The Times said the task force report also found that the FBI agents handling Rowe covered up his involvement in racial violence while a government informant inside the Klan. FBI guidelines formulated in 1975 are supposedd to prevent any recurrence of such activity.

Rowe told the Associated Press that he warned the FBI the Klan was planning to beat Freedom Riders in Birmingham in May 1961. "I was profoundly shocked that the U.S. government allowed that to take place." he said.

FBI agents who handled Rowe during the period reportedly said that such violence was an unfortunate but necessary part of an informant maintaining his cover.

There was one instance in the report, The Times said information from Rowe to the FBI prevented the possible murder of the Rev. Fred L. Shuttlesworth, a Birmingham civil rights leader.

Justice officials trying to fathom Hoover's actions in the church bombing case noted that the longtime director had poor relations with the Justice Department under Attorney General Robert F. Kennedy and operated the bureau as an unaccountable fiefdom rather than as the investigating arm of the department.