The National Security Department arrested a man in Mong Kok for allegedly importing seditious book to sell at a local bookstore.
It is understood the case involves a director of "Waiting Bird", a platform supporting incarcerated individuals.
According to its social media profile, its services include handling the purchase and sale of supplies for inmates and supporting detained individuals.
It was founded by former pro-democracy district councillor Chu Kong-wai.
Police stated that the National Security Department arrested a 34-year-old local male company director in Mong Kok this morning.
He is suspected of importing books in October this year for sale at a local bookstore, with intent to bring into hatred or contempt, or to excite disaffection against the Central Authorities and the HKSAR government.
Acting on a court warrant, police searched the arrested director's residence and office, seizing the seditious books in question.
Sources indicate that the arrested individual is not Chu Kong-wai.
"Waiting Bird" recently posted a shipment of 60 books arriving from Taiwan in mid-October is detained by Customs under the Hong Kong National Security Law.
The post emphasised the books involved were not new releases, had been imported from Taiwan more than once before, and were available at some local bookstores.