Talk about spoiling the party. On the eve of the 50th anniversary of D-Day, a former Soviet spy master has made headlines by alleging that another of the Allies' great triumphs, the Manhattan Project, was betrayed by its top scientists.

Niels Bohr, Enrico Fermi, J. Robert Oppenheimer and Leo Szilard -- gods of modern physics, all of them -- are said to have allowed critical documents about the atomic bomb to be passed on to the Russians. The scientists are all dead and unable to defend themselves, but many others have stepped into the breach.

Editorial writers have denounced, historians have assailed, critics have decried 86-year-old Pavel Sudoplatov and his book, "Special Tasks." Why should we believe you, they ask. Where is the evidence? Why are so many of your facts about the Manhattan Project wrong?

By this point, Time magazine, which played a leading role in spreading the news, is apologetic, while Little, Brown and Co., which is believed to have paid $850,000 for rights to the book, is less than thrilled with the return on its investment.

All the attacks must be hurting, says "Special Tasks" editor Roger Donald, "since the book is a bestseller overseas and isn't here." If given the chance to do it again, "I'd probably rethink the thing." Just how, he's not yet sure.

The American authors of the book, Jerrold and Leona Schecter, are holding firm. The Washington writers agree there's not much corroborating evidence, but say Sudoplatov's allegations must be taken seriously simply because of who he was: a lieutenant general who ran many of the Soviet Union's secret operations.

This seems reasonable until you watch the videotape the publisher has released of the Schecters interviewing Sudoplatov. The spy master is talking about how two of his operatives went to Denmark to get information from the great nuclear physicist Niels Bohr shortly after World War II.

"Denmark at the time had been recently liberated from the Germans by the Red Army," Sudoplatov says, "and attitudes in general to Soviet Russians were especially warm."

Comments John Keegan, a leading military historian: "Absolute rubbish." Denmark was liberated by the Brits, not the Reds.

If Sudoplatov can't get it straight who liberated Denmark, how is it possible to trust his unverified and maddeningly vague statements about the physicists? And if his veracity is uncertain, why were his assertions broadcast so widely last month?

The Claims

Taken as a whole, Sudoplatov's memoirs present a grim picture. The Administration for Special Tasks, which he headed, "was responsible for sabotage, kidnapping, and assassination of our enemies beyond the country's borders," he writes. Sudoplatov himself murdered a Ukrainian nationalist in 1938, claims credit for organizing the assassination of Leon Trotsky two years later, and directed guerrilla forces in Nazi Germany. After the 1953 downfall of his boss, chief of security forces Lavrenti Beria, Sudoplatov was arrested and sent to jail for 15 years.

"Special Tasks" has gotten some favorable reviews. On Sunday, the New York Times Book Review will list the autobiography on its recommended-reading list, describing it as "valuable."

But Chapter 7, called "Atomic Spies" and dealing with the Soviet infiltration of the Manhattan Project, has drawn numerous attacks. Sudoplatov never flat-out calls the four scientists spies -- something the Schecters are quick to underline.

"He says very carefully, both in the book and on videotape, 'These were not spies, God forbid,' " says Leona Schecter.

But Sudoplatov also says: "We received reports on the progress of the Manhattan Project from Oppenheimer and his friends in oral form, through comments and asides, and from documents transferred through clandestine methods with their full knowledge that the information they were sharing would be passed on."

Elsewhere, he underlines that "Oppenheimer, Fermi and Szilard ... were knowingly part of the scheme." If that's not spying, just what is it?

Yet the evidence in "Special Tasks" is slim, aside from a 1982 letter by Sudoplatov to the Soviet Central Committee referring to how his department got "the latest materials on atom bomb research ... from such sources as the famous nuclear physicists R. Oppenheimer, E. Fermi, K. Fuchs, and others."

Says Jerry Schecter: "We tried to check out as much as we could. But this is an oral history." Adds Leona: "We're presenting this man's memoir. He is the evidence we're presenting."

Sudoplatov has been in a Moscow hospital during much of this dispute. He's now home but is not giving any interviews.

As to why the details he offers are so sketchy, "He's leaving some things out, like the names of anyone who might be alive," says Leona. "The rule in intelligence is, you don't give live sources or tell exactly how you did it."

Remarks like these don't satisfy their critics. Thomas Powers, who eviscerates "Special Tasks" at length in the current New York Review of Books, says: "It's one thing to have an oral history of a man clearly in command of his faculties, and quite another to take one from someone who sounds like he's suffering from an age-related disability. Sudoplatov is incoherent."

Sudoplatov says Oppenheimer, the top scientist on the Manhattan Project, was influenced by his Soviet contacts to specifically ask for British physicist Klaus Fuchs to come to the laboratory at Los Alamos, N.M. Since Fuchs really was a spy -- he served nine years in prison and then went to live in East Germany -- this seems to finger Oppenheimer.

But, as Powers writes in the New York Review, "the huge record on the British mission establishes beyond doubt that Oppenheimer had nothing to do with bringing Fuchs either to America or to Los Alamos."

It's true that Oppenheimer was under suspicion throughout the war because of his past associations with Communists. He knew he was being watched, and is on record as telling a security officer in 1943 about overtures made by the Soviets to him and his staff. Would he do this if he were actually working for the Soviets?

Yes, says Leona Schecter: "It's very possible that this was a pattern of behavior to establish a cover."

No, says Richard Rhodes, author of "The Making of the Atomic Bomb" and one of the most vociferous critics of "Special Tasks."

"You have to look at this the way a court would," Rhodes says. "What's reasonable? What's provable? What's plausible? The security officer believed Oppenheimer to be a spy, had him followed day and night, and had his phones bugged. So Oppenheimer, who really is dealing with the Russians, tries to throw him off by saying he is being approached by the Russians? No one is that cool and that sophisticated."

For all the holes Rhodes and Powers punch in Sudoplatov's claims, they and the other critics have the essentially impossible task of proving a negative: that the four scientists weren't doing something treasonous. The Schecters, meanwhile, say that information yet to be released will eventually vindicate Sudoplatov.

The Discovery Channel, for instance, has been working for more than a year on a documentary called "The Red Bomb." Included will be an interview with Yakov Terletsky, one of the Soviets who went to see Bohr in Denmark in 1945 and supposedly elicited his guidance on what was wrong with the Soviet reactor.

In a letter published May 6 in the New York Times, the Schecters said that "Bohr's help to the Soviet Union is verified" by the Discovery interview with Terletsky. But the cable channel objects. "We are asking the Schecters to cease and desist in their claims. They have not seen our interview," a Discovery spokesman says.

A source says the interview with Terletsky, who died last year, both supports and contradicts Sudoplatov's assertions, and the Discovery producers are doing more investigating to find out where the truth lies. The documentary is scheduled to air in September.

The foreword to "Special Tasks" is by Robert Conquest. While not a specialist in either nuclear physics or intelligence matters, the senior researcher at the Hoover Institution is one of the leading Soviet affairs experts and thus a source of much of the initial credibility of "Special Tasks."

"All sources have mistakes. There's no such thing as the perfect source," he says, dismissing as "trivial" such errors as Sudoplatov's saying physicist Szilard was at Los Alamos when he never went there.

Conquest does, however, have some regrets about how Sudoplatov's revelations were marketed. "I wish it all appeared in the Journal of Oral History, if such a thing exists," the historian says. "The problem isn't the testimony, but how it was publicized."

The Reports

The public first learned about Sudoplatov's revelations in a three-pronged media assault on April 18. On that day, Time magazine appeared with a lengthy excerpt; the "MacNeil/Lehrer NewsHour" devoted a 27-minute segment to the charges; and copies of "Special Tasks" were distributed to other media and bookstores.

Until then, the book was a closely guarded project. Little, Brown didn't even put "Special Tasks" in its spring catalogue, fearing that "the controversy would have instantly begun," says Donald, the editor.

When Time bought serial rights to "Special Tasks," it explicitly agreed not to blow the project's confidentiality by doing any independent reporting. In essence, it accepted the contents as fact. "MacNeil/Lehrer" did not pay any money but was given its exclusive under the same conditions.

"There is no evidence that Time or 'MacNeil/Lehrer' asked any questions except 'Is it libelous?' " says Powers, author of "Heisenberg's War," about the German attempt to build an atomic bomb. Even Conquest, the Schecters' firm defender, calls the nine-page Time treatment, with its stark red and black headlines, "sensationalized."

Time Managing Editor James Gaines now has some regrets.

"We couldn't exercise our normal fact-checking procedures or call the usual suspects, because it would be violating the confidentiality agreement," Gaines says. "Given that, we should have made it clear that the usual standard of accuracy for Time magazine pieces did not apply in this case."

The fact that Time and Little, Brown are both parts of Time Warner Inc. had no bearing on the serialization, Gaines says. However, the fact that Jerry Schecter was also a member of the family -- he was chief of Time's Moscow bureau from 1968 to 1970 -- did "raise our confidence."

Now that confidence appears shaken. "I certainly was dismayed by the number of apparent factual errors," says Gaines. "I was under the impression that more vetting was done. I was under the impression it was more than oral history." Last week Time ran a follow-up article, saying the critics "cite enough errors, inconsistencies and implausibilities to make a troubling case."

"MacNeil/Lehrer" executive producer Lester Crystal is unrepentant. "I thought we did a careful, non-sensational job, raising some good skeptical questions," he says, although he adds, "I understand why some people are upset."

On April 26, "MacNeil/Lehrer" broadcast a second segment: a summary clip of the original, plus the Schecters and two of their critics hashing it out. "We felt comfortable {with the first show} because we had every intention of following it up," Crystal says. "We knew it wasn't our last shot."

Powers still can't believe it. "It's shocking that 'MacNeil/Lehrer' would treat the reputations of Oppenheimer, Fermi, Bohr and Szilard with such casualness. They wouldn't dream of doing it about anyone who was alive and had a lawyer."

The Publisher

"I certainly knew the book was going to be attacked," says editor Donald. He's not too bothered by the errors. "I refer you to Khrushchev's memoirs," which Jerry Schecter worked on and Little, Brown published in three volumes.

With the first volume, Donald said, "there was an attack that went on for a month. Any number of historians and members of the media said it was false on the grounds of internal evidence -- that there were mistakes in it that Khrushchev could not possibly make." Nevertheless, the memoirs are now accepted as authentic.

While Donald says he believes Sudoplatov "had a valid piece of historical testimony," it wasn't up to Little, Brown to prove it. "You have to understand the nature of book publishing... . A book publishing house does not have reporters, does not have investigators. When an author signs a book contract, he warrants he has the right to use the material and he warrants its accuracy." Thus the burden of veracity falls most heavily on the writer.

Says St. Martin's Press Chairman Thomas McCormack: "There is tremendous variation in the responsibility of the publisher for investigating the truth. Some of them do one hell of a lot less than others."

And then, when the press takes up the story, distortions become almost inevitable. "This kind of fallacious story has a way of snowballing," says Donald Lamm, the chairman of the publisher W.W. Norton. "What you have in the case of 'Special Tasks' is information out of control."