The firm has also published novels depicting the daily lives of Hongkongers.

Sources said Humming Publishing was also barred from joining the fair this year. The firm could not be reached for comment.

The council declined to comment on the two cases, saying: “In organising any event, it is not uncommon that some applications may not be successful. We do not comment on individual cases.”

The two firms are the latest to face the same fate as independent publisher Hillway Press, founded by political activist and author Raymond Yeung Tsz-chun, which revealed earlier that it was not allowed to join this year’s fair. It said the council had not given it a reason.

Yeung was arrested and charged in April for allegedly taking part in illegal assemblies during the 2019 social unrest. The case is expected to be heard in July. During a protest in June that year, he was allegedly hit in the right eye by a police projectile.

Referring to his rejection, Wong said the council’s decision lacked “credibility and morality”.

“We’ve put in a lot of resources to prepare for the book fair, which could generate over one-third of our annual income. Failure to take part in the fair will affect our book sales,” he said.

Wong added that he had become very careful with selecting publishing content since the enactment of the national security law in late June 2020.

“Last year someone had complained to the [trade council] that our books had breached the national security law and immediately we received reminders from the council,” he said.

Wong said that since a publisher had been arrested for allegedly threatening national security, “we have been very careful to make sure that we won’t run afoul of the law. For criticisms about the government, we strive to be objective and fact-based”.

Wong stressed it had become more difficult for publishers to find writers to attempt different content and create literary works.

“Some people have lost interest in writing and even quit the industry,” he said.

Jimmy Pang Chi-ming, a cultural critic and boss of maverick publisher Subculture, said the company would not take part in this year’s fair for the first time in 30 years as it had not published any new books.

“No writer is willing to write in Hong Kong now. They’ve totally lost interest in publishing a book following the enactment of the national security law,” he said. “In the past, we published at least 20 books just for the fair, but this year we can’t publish even one.”

The publisher is well-known for its satirical comics such as Silly Old Tung and Broom-head Ip which lampooned the city’s first chief executive Tung Chee-hwa and lawmaker Regina Ip Lau Suk-yee. It has published books across different genres, including political commentary, comics and novels.

“Hong Kong’s publishing industry is dying,” he said. “When a society is denied creative freedom and the freedom of speech, its publishing industry will cease to survive.”

In July last year, Hong Kong national security police arrested and later charged five speech therapists for publishing a series of allegedly seditious children’s books, accusing the group of inciting anti-government hatred and instigating violence. The picture book series depicted sheep defending their village from invading wolves.

This year’s book fair is expected to be held at the Convention and Exhibition Centre in Wan Chai from July 20 to 26.