The announcement yesterday by Stern magazine that it had discovered 60 diaries said to have been written by Adolf Hitler came as no surprise to some U.S. publishers. They had been engaged for weeks in a heated bidding war for the right to serialize the material.

As of yesterday afternoon, U.S. rights to the purported diaries apparently had not yet been sold. It was widely assumed, however, that press mogul Rupert Murdoch, owner of the New York Post and several other papers, who already had secured the British and Australian rights, would eventually emerge the winner. But New York Post officials said yesterday that they had heard of no such plans. Murdoch could not be reached for comment.

The U.S. competition began early this year when Stern, one of West Germany's most popular magazines, engaged agent Lynn Nesbit of International Creative Management in New York to handle sales of United States and Canadian serial rights to what was then thought to be the entire set of diaries. By March, Nesbit said yesterday, half a dozen publishers had expressed interest, and Newsweek finally submitted the highest bid.

But when she reported Newsweek's undisclosed offer back to Stern, "they said they had found more documents and wanted to open up the bidding worldwide," Nesbit said. At that point, she was paid her commission and withdrew from the fray. Stern, however, is reportedly still entertaining bids.

Iain Calder, president of the National Enquirer, said yesterday from the tabloid weekly's Florida offices that, "right now, we are involved in negotiations with Stern," but would have no definitive statement until after Stern's Monday press conference on the authenticity of the manuscripts.

Stern said yesterday that the diaries, which cover the years 1932 to 1945, had been discovered by a group of reporters during a three-year search through Europe and Latin America. According to the magazine, a verification team including Cambridge historian Hugh Trevor-Roper has pronounced the writings genuine, but many German specialists remain skeptical.

Meanwhile, the major newsweeklies appear to be out of the running. In response to all questions about the diaries yesterday, Time issued only a terse statement: "We have had an interest." Newsweek put out a similar announcement, explaining that some of its "editorial and corporate executives had discussions with Stern," but were "unable to agree on terms and editorial conditions and withdrew." Life was never in the race. "We haven't been involved at all," managing editor Richard Stolley said yesterday. "I just heard about it today."

Among the many rumors circulating in publishing circles yesterday was that Bantam Books was planning to bring out a bound version of the diaries. Bertelsmann, the West German corporation that owns Bantam, also owns a large portion of Stern's parent company, Gruner & Jahr. But Bantam Vice President Stuart Applebaum said yesterday that "we have a great interest in the possibility of doing a book someday related to the diaries, but at this time we have no plans to publish one. Nor do we have any deal to do one."