China’s top agency in Hong Kong praised the arrests of four members of a group that had organized an annual Tiananmen Square vigil as authorities continued a broader push against local pro-democracy activists.

The Liaison Office said in a statement Wednesday that the arrests of four people on accusations of failing to comply with Beijing-drafted security legislation reflected the "fairness and justice of the law.” Earlier, police had arrested four members of the Hong Kong Alliance in Support of Patriotic Democratic Movements of China — Chow Hang-tung, Leung Kam-wai, Tang Ngok-kwan and Chan Dor-wai — local media including Now TV reported.

The arrests come after Security Secretary Chris Tang vowed "swift and efficient” action against the activist group over its refusal to cooperate with a national security investigation and hand over related documents. Police said in statement they arrested four people for failing to comply with security law requirements, without naming the suspects.