A few years ago, the Chinese writer Murong Xuecun had the kind of career most novelists dream about. His eight books had sold two million copies in China, and he had amassed more than eight million social media followers.

But in 2011, he decided to stop publishing. He was afraid of running afoul of Chinese censors, and was even more concerned about the self-censorship that had crept into his work. Now he wishes he had never published some of his earlier books, which tiptoed around political issues.

“When I look back on them, I feel ashamed of myself,” said Mr. Murong, 41, who lives in Beijing and whose real name is Hao Qun.

Mr. Murong was among a handful of writers who gathered on the steps of the New York Public Library on Wednesday night to protest the limits on free speech and expression in China. The gathering, organized by the PEN American Center, was prompted by the presence of a large delegation of Chinese publishers at BookExpo America, a major publishing trade event taking place in Manhattan this week.

The juxtaposition was striking. This week, thousands of booksellers, librarians, publishers and authors mingled at BookExpo, at the Jacob K. Javits Convention Center, where Chinese publishers were being feted as international guests of honor. To mark the event, the Chinese government sent a 500-person delegation from 100 publishing houses, and 26 of its top authors. Chinese publishers claimed close to 25,000 square feet of floor space at the hall and planned 50 events around the city, including poetry readings, film screenings, author panels and presentations from its largest publishers.

Not many blocks away, Mr. Murong stood on the library steps and read aloud from an open letter he had written to Chinese censors in 2013, after his social media account was blocked and its contents deleted. “You treat literature as poison and free speech as a crime,” he said. (Mr. Murong is also a contributing opinion writer to The International New York Times.)

He was joined by prominent American writers like Jonathan Franzen, Paul Auster, Francine Prose and A. M. Homes, and by the China-born novelists Ha Jin and Xiaolu Guo. They took turns reading works by Chinese authors who are in prison or under house arrest for their writing, including the Tibetan poet Tsering Woeser, the writer Liu Xia and her husband, the poet and Nobel Peace Prize winner Liu Xiaobo, who is serving an 11-year prison sentence for subversion.

“There are all of these writers in China who are in jeopardy for expressing themselves, and if you have a government-sanctioned delegation, you’re only getting part of the story,” said Suzanne Nossel, executive director of the PEN American Center, an organization that promotes free speech.

BookExpo’s organizers called China’s featured role at the expo an unprecedented and historic meeting between the world’s two largest publishing industries.

“We’re going to remember this for a generation, because it’s going to be the beginning of opening some doors,” said Steve Rosato, the event director for BookExpo. He said the event was not an appropriate forum to address censorship.

 “We’re not in the position to do anything around that,” he said when asked about PEN America’s objections. “China is a significant market and they represent a significant trade opportunity.”

China’s prominence at this year’s BookExpo highlights both the growing interplay between Chinese publishers and the international literary community, and the difficulties of doing business when standards for freedom of expression differ significantly.

China has accelerated its effort to export books and authors as part of a broader strategy to exert “soft power” by raising its cultural profile internationally. Chinese publishers have heavily promoted their catalogs at the London and Frankfurt book fairs in recent years.

Major deals are taking place between American and Chinese content companies. Earlier this year, the American e-book distributor Trajectory signed a deal with a Chinese digital company, Tencent, to distribute Tencent’s catalog of 200,000 Chinese e-books in North and South America.

“Western publishers are interested in getting access to the Chinese market, and the Chinese government is interested in getting more authors known in the West,” said Jeffrey N. Wasserstrom, a history professor at the University of California, Irvine, and author of “China in the 21st Century.”

Some American publishers say that their business is booming in China and that they have not faced significant government interference.

“The Chinese appetite for Western books is really impressive,” said Niko Pfund, president of Oxford University Press. “I’ve been amazed and pleasantly surprised by how smooth and uncomplicated it has been.”

The Chinese book business has ballooned into an $8 billion industry, the second largest after the United States. Chinese publishers released 444,000 titles in 2013, up from around 328,000 in 2010. The country is adding around 20 million new English speakers a year.

Chinese publishers have been eagerly acquiring Western titles, especially by British and American authors. In 2013, they bought the rights to more than 16,000 foreign books, including nearly 5,500 from America, more than double the number purchased a decade earlier. HarperCollins exported around 9,700 English-language titles to China in 2014, and cites China as one of its fastest growing international markets. Business books and children’s books are among the most popular categories, it says.

Penguin Random House said that it exported more than 50,000 of its English-language print and e-book editions to China annually.

“Chinese people are very curious about culture in other countries,” Wu Xiaoping, president of Phoenix International Publishing Group, said in an interview through a translator after appearing on a panel at BookExpo. “There will be more and better relationships between Chinese and U.S. publishers.”

When asked whether certain topics were off limits for writers and if his publishing house adhered to government guidelines, he replied, “No comment.”

In China, censorship — and, more commonly, self-censorship — has long been a feature of the publishing industry, which is controlled by the ruling Communist Party. The government’s roughly 580 state-run publishing houses ensure that domestic fare does not broach so-called sensitive topics: gay rights, the discontent of China’s ethnic minorities, and the bloody crackdown on pro-democracy protests of 1989.

“Chinese censorship works before the writer even starts writing,” said Bao Pu, publisher of the New Century Press in Hong Kong, who participated in the PEN event. “Why write a piece that you know will never get published?”

Western writers who publish their work in China are not immune to the country’s more rigid standards. Some, like the scholar Ezra F. Vogel, have reluctantly cooperated with publishing house censors. The mainland Chinese version of his biography on Deng Xiaoping omitted a number of adjectives about Mao Zedong and entire passages about Deng, but Mr. Vogel has said that the deletions were necessary to reach an audience hungry for mostly unexpurgated history about their country.

In a few cases, writers have backed out of publishing deals rather than submit to censorship. Evan Osnos, the author of “Age of Ambition,” a book about economic and social change in China, decided not to publish a translation in mainland China after editors there told him they would delete references to the artist Ai Weiwei and Mr. Liu, the jailed Nobel Peace Prize winner. “To me, making those cuts wouldn’t be engaging Chinese readers, it would be isolating them,” he said in an email.

Other writers were never consulted about changes made to their work, and learned only after publication. The writer Andrew Solomon was infuriated to learn that “The Noonday Demon,” his book about depression, had been altered without his approval, omitting his references to being gay.

“I think there’s a suggestion that because China is an enormous market, we have to defer to the Chinese internal standards of censorship,” Mr. Solomon said. “It’s somewhere between naïve and hypocritical to engage with China and not acknowledge the severity of this problem.”