As Carrie Lam spoke, groups of officers in riot gear conducted stop-and-search operations along an expected protest marching route.

Foreign Secretary Dominic Raab said Sunday that Britain's government has reviewed extradition arrangements with Hong Kong, and that he plans to make a statement in parliament on Monday over the topic.

The primaries come less than two weeks after Beijing imposed sweeping national security legislation on the Asian financial hub, stoking concerns that wide-ranging freedoms not seen in mainland China will be crushed.