The novelist Junot Díaz was in a relaxed and playful mood on a panel at a writers festival in Australia on Friday, until he received an unexpected question near the end of the session.
The writer Zinzi Clemmons stood up. Without identifying herself by name, she asked Mr. Díaz about a recent essay he had published in The New Yorker detailing the sexual assault he experienced as an 8-year-old boy. She then asked why he had treated her the way he had six years prior, when she was a graduate student at Columbia.
An uncomfortable murmur arose from the audience at the Sydney Writers’ Festival, according to attendees.
Hours later, the confrontation erupted into a major scandal in the literary world, when Ms. Clemmons repeated her accusations in front of a wider audience, on Twitter. Ms. Clemmons, who teaches writing at Occidental College in Los Angeles, said in a tweet that when she was a graduate student, Mr. Díaz had forcibly kissed her. Her claims swiftly set off other accusations of abusive and inappropriate behavior by Mr. Díaz.
“As a grad student, I invited Junot Díaz to speak to a workshop on issues of representation in literature,” she wrote on Twitter. “I was an unknown wide-eyed 26-year-old, and he used it as an opportunity to corner and forcibly kiss me. I’m far from the only one he’s done this to, I refuse to be silent anymore.”
Ms. Clemmons said she believed that Mr. Díaz had tried to pre-empt accusations like hers by writing the autobiographical essay in The New Yorker last month in which he said that he had been raped as a child by an adult he trusted. In the essay, Mr. Díaz said that after the assault, he began to suffer from depression and “uncontrollable rage,” and later had troubled relationships with women and problems with fidelity.
In a statement provided through his literary agent, Nicole Aragi, Mr. Díaz did not address the specific accusations, but said he took responsibility for his past behavior.
“I take responsibility for my past,” he said. “That is the reason I made the decision to tell the truth of my rape and its damaging aftermath. This conversation is important and must continue. I am listening to and learning from women’s stories in this essential and overdue cultural movement. We must continue to teach all men about consent and boundaries.”
Mr. Díaz’s publisher, Riverhead Books, did not respond to a request for comment. The New Yorker declined to comment. A spokeswoman from M.I.T., where Mr. Díaz teaches writing, declined to comment, noting that she was still learning about the situation.
Ms. Clemmons, in a statement to The Times, said: “Junot Díaz has made his behavior the burden of young women — particularly women of color — for far too long, enabled by his team and the institutions that employ him. When this happened, I was a student; now I am a professor and I cannot bear to think of the young women he has exploited in his position, and the many more that would be harmed if I said nothing.”
The tweet from Ms. Clemmons, whose debut novel, “What We Lose,” was published by Viking in 2017, prompted allegations of verbal abuse from other writers.
The short-story author Carmen Maria Machado, responding to Ms. Clemmons’s tweet, said that Mr. Díaz had become angry with her when she was a graduate student and had argued aggressively with her for an unusually long time after she criticized one of his character’s relationships with women.
Another writer, Monica Byrne, said that when she was 32, she had sat next to Mr. Díaz at a dinner and that he had yelled in her face after they disagreed. “It was completely bizarre, disproportionate and violent,” she said on Twitter. She added that she had heard stories worse than her own.
Mr. Díaz is the latest author to face claims of harassment and misconduct, and is perhaps the most prominent. Born in the Dominican Republic and raised in New Jersey, he has been celebrated as one of his generation’s most gifted and inventive fiction writers. His novel “The Brief Wondrous Life of Oscar Wao” won the Pulitzer Prize in 2008, and drew rapturous reviews. He received a MacArthur genius grant in 2012. He recently published his first children’s picture book, “Islandborn.”
The publishing industry has been struggling to deal with the fallout from sexual harassment scandals in recent months, as allegations against authors have led to canceled book deals, boycotts by bookstores and even pulped books. Some publishing houses have added “morals clauses” to their contracts, which allow publishers to cancel deals if an author is accused of harassment or other unethical behavior.
On Friday, the Swedish Academy announced that it would delay the 2018 Nobel Prize in Literature until next year, because of a sexual harassment scandal that has engulfed the academy after one of its associates was accused of sexual assault.
Earlier this year, several prominent children’s book authors and illustrators, among them James Dashner, Jay Asher and David Diaz, faced harassment accusations from multiple women. Mr. Dashner and Mr. Asher were both dropped by their literary agents, and Mr. Diaz’s illustrations for a forthcoming book were scrapped. After several women accused the novelist Sherman Alexie of sexual misconduct in an NPR report, Mr. Alexie asked his publisher to delay the paperback publication of his memoir, and declined to accept the 2018 Andrew Carnegie Medal for nonfiction.
It was not immediately clear what career repercussions Mr. Díaz might face following the accusations. Some booksellers, including Quill Books & Beverage in Westbrook, Me., and Duende District, a pop-up bookstore, said they would no longer sell his books.
The Sydney Writers’ Festival also announced Saturday that he had withdrawn from his coming appearances, and would return to the United States. Asked for a response after her own event at the festival — a conversation with Glory Edim that included blunt discussions of race, #MeToo and feminism, but no mention of Mr. Díaz — Ms. Clemmons said: “He did the right thing and left. That’s my statement.”
The allegations against Mr. Díaz came as a shock to some in the literary world, but other responses to the news on social media suggested that there had long been rumors about his behavior toward women. Several prominent writers, including Cheryl Strayed, Alexander Chee, Celeste Ng, and Jesmyn Ward responded to Ms. Clemmons’s tweet, expressing sympathy and support.
“Everyone in the literary world/the media knew this, or suspected it. And yet, when Junot Díaz published his New Yorker essay — a pre-emptive strike if there ever was one — we gave him nothing but plaudits,” EJ Dickson, an editor at Men’s Health Magazine, wrote on Twitter on Friday.
In his New Yorker essay, Mr. Díaz noted that the abuse he experienced as a child had never stopped affecting him, writing, “No one can hide forever. Eventually what used to hold back the truth doesn’t work anymore. You run out of escapes, you run out of exits, you run out of gambits, you run out of luck. Eventually the past finds you.”