Hong Kong’s publishing industry is facing increasing pressure from China to censor books deemed sensitive by the ruling Communist party, PEN America said in a report, with a raft of store closures and a shrinking pool of willing publishers.

The report comes a year after five Hong Kong book publishers were detained by Chinese authorities, with some abducted and whisked across borders from Thailand and Hong Kong and held incommunicado for months. All of them specialised in books on the private lives of the top leaders and the intrigues among the Chinese elite.

Of the five, Gui Minhai, who disappeared from a holiday home in Thailand, remains in custody in mainland China while the other four could be rearrested if they return and are thought to still be under surveillance by Chinese authorities. Another one of the book sellers, Lee Po, is a British citizen.

After the UK handed Hong Kong to China in 1997, the city retained many freedoms, including freedom of speech, under a framework known as “one country, two systems”, which has made the city a base for many critical of the Chinese government. But many, both within the city and overseas, fear those liberties have been eroded in recent years.

“As Hong Kong residents grapple with continued encroachments by Beijing, the future of free expression on the island and its status as the regional publishing hub is in question,” said Suzanne Nossel, Executive Director of PEN America.

“The government of Hong Kong must act decisively, now, to buttress the rule of law and the ‘one country, two systems’ framework that protects creative freedom and has allowed Hong Kong to serve as such a vibrant commercial center.”

Of the 16 bookstores that sold politically sensitive material at Hong Kong’s airport, a key point for curious mainland Chinese to purchase titles critical of Communist leaders, 11 have shut in the past year. Book stores specialising in political material in downtown Hong Kong also saw a raft of closings.

Yu Jie, an exiled writer and democracy activist, had one of his books shelved by a publisher that had previously released his work. He approached several other outlets, all of whom turned him down, alluding to the disappearances.

“One publisher told me that his relatives told him they didn’t want him to be a second Lee Bo,” Yu said of his efforts.

Earlier this year at the Hong Kong book fair, the premiere event in the city’s literary calendar, there was a notable decline of stalls carrying political and ‘banned” works.

While titles that cannot find a Hong Kong publisher are usually still released in nearby Taiwan, publishers there complained that very few in Hong Kong are willing to distribute the books, the report said.

PEN America decried the weak response from the Hong Kong authorities and the British and Swedish governments for not doing enough to protect their citizens, accusing the international community of prioritising business ties over human rights.

“There are other incentives for governments to downplay Chinese abuses, including, above all, the desire to maintain beneficial trade and economic relationships,” the report said.