Hong Kong Education Bureau has recommended schools to review their book collections and remove those titles that may breach the draconian national security law.
"If any teaching materials including books have content which is outdated or involve the four crimes under the law, unless they are being used to positively teach pupils about their national security awareness or sense of safeguarding national security ... they should otherwise be removed from the school," a spokesperson for the bureau was quoted as saying by by South China Morning Post.
"Schools have a gatekeeping role in terms of choosing suitable teaching resources. The bureau would take serious follow-up actions if any problems arise over the issue," he added.
Earlier on Sunday, South China Morning Post had reported that Hong Kong libraries have taken at least nine titles written by localist or democracy advocates out of circulation for conducting a review of whether the books run afoul of the new national security law.
Bar Association chairman Philip Dykes had called the move to be alarming and said authorities needed to justify restricting the public's right to seek information.
The Leisure and Cultural Services Department, which manages the city's public libraries, had confirmed it was scrutinising some books for compliance with the new law, without naming them.
The Chinese-language books were written by activist Joshua Wong Chi-fung, localist Horace Chin Wan-kan and Civic Party lawmaker Tanya Chan. A search of the nine titles on the library website on Saturday found all the titles marked "under review".
Beijing drafted and passed the legislation late last month that targets acts of secession, subversion, terrorism and collusion with foreign forces, with punishments of up to life in prison for the most serious offences.
The move came after months of social upheaval triggered by opposition to a now-withdrawn extradition bill but that morphed into wider demands, including universal suffrage.
( With inputs from ANI )