The government’s campaign is in tandem with recent efforts by mainland China’s central government, itself a core target of antigovernment demonstrators, to assert more stridently what it perceives as its right to intervene in the affairs of the semiautonomous Chinese territory.

These moves have raised concerns in Hong Kong that China’s ruling Communist Party is pressing for restrictions that would curb the protests, which were among the biggest challenges for China’s leader, Xi Jinping. Many fear that such restrictions, which could include a widely contested national security law, would accelerate the erosion of civil liberties in Hong Kong, a former British colony that enjoys freedoms unseen on the mainland.