A public consultation period for a new Hong Kong national security law closes on Wednesday amid concerns that the legislation, which authorities want to put in place soon, will further erode freedoms in the financial hub.

The law, known as Article 23, is aimed at addressing what officials call deficiencies or loopholes in the national security regime, which was bolstered just four years ago by another national security law imposed directly by Beijing.

It will target crimes including treason, theft of state secrets, espionage, sabotage, sedition and "external interference" including from foreign governments. The Hong Kong legislature, which is dominated by pro-Beijing lawmakers, is expected to approve it.