The London Sunday Times published the first excerpts from what are said to be Adolf Hitler's secret diaries tonight as historians debated their authenticity.

The newspaper reported that American, Swiss and West German handwriting experts had concluded that samples of the material were written by Hitler. But it also disclosed that the one leading historian of the period to examine the diaries--Hugh Trevor-Roper of Britain--concluded that they were authentic after only one afternoon's study. Trevor-Roper said the archive is "the most significant historical event of the last decade."

Other historians, without having seen the documents, continued to voice skepticism about them. Britain's Alan Bullock called for West Germany to establish an international commission to make a definitive study. "Otherwise," he said, "a lot of political use is going to be made of this . . . and everybody will still be in the dark."

The Times, sister paper of the Sunday Times, said in a lengthy article by Trevor-Roper published this morning that the diaries will "significantly alter historical judgments on Hitler's strategic thinking, exercise of power and personality."

This morning's paper in announcing what would be disclosed in the Sunday Times said that the diaries reveal that Hitler approved the flight of Rudolf Hess, Hitler's deputy, to Scotland in May 1941 to seek peace with Britain. Hitler denounced Hess as insane when he was captured. The diaries, by contrast, say that it had been agreed that should Hess' mission fail, he would feign insanity and remain silent. Hess, 89, is now serving a life sentence for war crimes in Spandau prison in West Berlin.

The article also said that according to the diaries Hitler allowed the British Army to escape at Dunkirk in 1940 when France was falling to the Nazis because Hitler hoped to negotiate for peace with the British.

The Times said Hitler "never hints that he had any direct knowledge of or hand in organizing the Holocaust" deaths of 6 million Jews. But it said he wrote that if the Jews "could not be resettled in the East and since no other country would accept them, they should be sent to the sea and the boats sunk."

In its initial installment, The Sunday Times, which purchased British rights to the 60 volumes of diaries and other papers from the West German magazine Stern, provided only a series of brief quotes, mainly describing Hitler's view of various wartime personalities. Also included is what is said to be the diary's final entry, written in April 1945 as the Allies encircled Berlin. "The long-awaited offensive has begun," Hitler wrote, "May the Lord God stand by us."

The bulk of The Sunday Times' four-page report deals with how the material was found and what efforts were made to prove it is genuine.

The newspaper said that the diaries were located by Gert Heidemann, 51, a West German journalist who painstakingly tracked them down in 1981 to an unidentified former Nazi air force officer. According to Heidemann, the archive had been retrieved from a plane that crashed in what is now East Germany in the closing days of World War II.

In a key test of authenticity, handwriting experts were each given five undisputed examples of Hitler's writing taken from official West German archives and then samples from the purported diaries, The Sunday Times said. Ordway Hilton, 69, of Landrum, S.C., and formerly of New York, described by the newspaper as "authoritative" and an "examiner of disputed documents," said of the samples: "They were written by Hitler."

Max Frey-Zuler, head of the scientific branch of the Zurich police and, according to the newspaper, "one of Europe's best-known graphologists," said, citing characteristics of the writing: "There can be no doubt that these samples were written personally by Hitler."

The paper said experts employed by the police of the West German state of Rhineland-Palatinate, who also work for the central government archives, certified: "It is a probability bordering on certainty that these documents were written by Adolf Hitler."

Trevor-Roper explained in Saturday's Times why he is "satisfied that the diaries are authentic." Although initially skeptical, he wrote, "when I had entered the back room in the Swiss bank where the material was being kept and turned the pages of those volumes, my doubts gradually dissolved. . . ."

Trevor-Roper, who is master of Peterhouse College at Cambridge University, has devoted his career to the study of Hitler and has published a number of books, including three collections of Hitler's documents. The Sunday Times said that the historian "would have liked more time" with the material and expressed reservations about the superficiality of summaries of portions he did not see that were provided to him by Stern--which begins publishing excerpts Monday.

Nonetheless, his overwhelmingly positive finding shows, as the newspaper asserted, that Trevor-Roper has "staked his academic reputation on the conclusion."

Among the skeptics is British writer David Irving, who said he believed the archives to be East German forgeries offered to him last year. "It is all part of the same setup," he said. "The same people seem to be involved."

According to The Sunday Times, Heidemann, the journalist who located the material, was a collector of Nazi-era memorabilia. From his contacts, he learned of reports that an archive of Hitler documents had gone down in a plane crash, which he traced to a village in East Germany. Interviews with witnesses and, eventually, survivors finally led him to a former Nazi air force officer living in Switzerland who knew that the material had been hidden in a hayloft in East Germany, the newspaper said.

The account goes into detail on how Heidemann traced the site of the plane crash but offers little information on how he actually gained possession of the documents, how much was paid or how they were smuggled out of East Germany. The Sunday Times said Heidemann refused to disclose that information because it might endanger the lives of persons "still living behind the Iron Curtain."

Among the quotes published by The Sunday Times are a 1932 diary entry that "I shall keep my political actions and thoughts in notes in order to preserve them for posterity like every other politician." He refers critically to several of his closest aides, calling Heinrich Himmler "a deceitful small-animal breeder" but praising Martin Bormann. "This man Bormann has become indispensable to me," he wrote near the end of the war. "If I had five Bormanns, I would not be sitting here now."