Hong Kong's top security official has warned booksellers to closely examine the titles they sell after police action involving two bookstores. The remarks came a day after five people linked to the shops were arrested, adding to pressure on the city's independent book trade.

Officials said sellers should make sure their inventory does not harm national security. The message indicates that bookstores remain under heightened scrutiny as authorities continue applying national security standards to publishing and retail activity.

The latest police operation is reported to be the third round of arrests targeting independent bookstores in the past four months. That pattern points to an ongoing enforcement push rather than a one-off incident, especially for smaller outlets that may carry politically sensitive works.

The developments are likely to deepen concerns about the impact of national security enforcement on expression and cultural life in Hong Kong. For booksellers, the latest warning underscores that decisions about what appears on shelves can bring legal and political consequences.