President Franjo Tudjman of Croatia has apologized for a book in which he cast doubt on whether 6 million Jews died in the Nazi Holocaust.

In a letter delivered Monday to Kent Schiner, international president of B'nai B'rith, Tudjman said that since the 1989 publication of "Wastelands of Historical Reality," he has developed a "different perspective" about world Jewry than when he wrote the book as "a persecuted dissident" in what was Yugoslavia.

"It is in terms of my evolving relationship with and increased understanding of the Jewish people that I now realize the hurtfulness of certain portions of this book and the misunderstanding they have caused," Tudjman said in the letter.

"For this I offer an apology, both as the president of a newly independent state which wishes to forge a firm and enduring friendship with the Jewish people, and as a human being who desires to make amends in furtherance of such a friendship."

Controversy over Tudjman's book reached a peak when he came here last April for the dedication of the U.S. Holocaust Memorial Museum. At the time, Elie Wiesel, a Holocaust survivor who spoke at the dedication ceremony, called Tudjman's presence "an outrage."

Tudjman's letter of apology had its origins in the Croatian leader's visit here, according to George Spectre, associate director of B'nai B'rith for international affairs.

Spectre said yesterday his organization had concluded that Tudjman's book was "clearly a work of antisemitism cloaked in scholarly terms that sought to portray Jews as villains throughout history."

In addition, Spectre said, B'nai B'rith had rejected Tudjman's claims that the antisemitism issue had been caused by mistranslations or by distorted and unauthorized versions circulated by Yugoslavia's old communist government or Croatia's rival state, Serbia.

As a result of B'nai B'rith's complaints, Spectre was among a small delegation of American Jews invited to meet with Tudjman in his hotel suite here last April 20.

"Tudjman refused to discuss the antisemitism issue," Spectre recalled. "Whenever someone brought it up, he stonewalled. At the end, he called in a Croatian television crew to film the meeting with American Jews, and I was so angry that I walked out in protest."

Then, Spectre continued, about three months ago, he was contacted by the small Croatian Embassy here. "They said they wanted to discuss ways in which this matter could be resolved and put behind us, and it soon became apparent that they were acting on Tudjman's behalf," Spectre said.

According to his account, the result was a dialogue with Ambassador Peter Sarcevic and his deputy, Kresimir Cosic, about what would constitute an appropriate gesture on Tudjman's part.

"President Tudjman wanted to make it clear that neither he nor our country is antisemitic and that there should be no misunderstanding about that," Cosic said yesterday.

"Croatia obviously has an agenda," Spectre said in reference to the Balkans war and the territorial clashes Croatia has had the past 2 1/2 years with neighboring Serbia and Bosnia-Herzegovina. "B'nai B'rith made clear throughout that we did not see this as an occasion for taking sides, and we insisted on keeping the focus solely on the antisemitism issue."

B'nai B'rith representatives pointed out that despite the controversy over his book, Tudjman has had good relations with Croatia's tiny Jewish population and with Israel, and argued that an apology would entail what Spectre described as "no loss of dignity."

On Monday, that argument finally bore fruit when B'nai B'rith officials went to the Croatian Embassy to receive Tudjman's letter.