Authorities have clamped down on publications allowed at the annual Hong Kong Book Fair, one of the largest in Asia, since a national security law was imposed on the city in 2020 by Beijing.

The alternative festival, held at Hunter Bookstore, promoted publications covering issues including minority groups, the LGBTQ community and the city's wide wealth gap.

"The biggest difference for us (from the government-run fair) is that we have no censorship," bookstore owner Leticia Wong told reporters.

At least two publishers in attendance had removed books from their booths at last year's Hong Kong Book Fair, after officials said they contained "sensitive content".

The books included a travel book by journalist Allan Au, who was arrested in 2022 for allegedly conspiring to publish "seditious materials".

The publisher's application to take part in this year's book fair was rejected without explanation.

- 'No censorship' -

Beijing imposed its national security law on Hong Kong following huge and sometimes violent pro-democracy protests in 2019, and critics say the law has crushed the city's once-vibrant civil society.

A survey of 19 independent publishers in Hong Kong released on Sunday found their freedom of expression had been undermined by the national security law, and most relied on independent bookstores to distribute their works.

"I can see that the government is becoming more and more selective in exhibitors," said Lee, a 22-year-old university student who refused to give his full name for safety reasons.

The independent fair at Hunter Bookstore offered more options, he added.

Leslie Ng, an editor for Bbluesky -- a publisher barred from this year's Hong Kong Book Fair -- said the government-run festival used to be diverse and supportive of publishers, but that had changed.

The biggest challenge publishers face now, he said, is the lack in freedom of speech.

"We are always thinking about whether or not we will break the law" when editing books, Ng told AFP.

"The red line is very blurry, and we are so scared as we don't know where it is."

Hunter Bookstore's Wong believes her fair showcases the "unique landscape" of Hong Kong's publishing scene.

"Book fairs are not supposed to be censored, and independent publishing deserves more attention," she said.

"Book-lovers and those who care about freedom of publication, reading and writing should treasure this value."