Riot police flooded the streets as protesters gathered ahead of a debate on the bill that once enacted will criminalise abuse of China's national anthem in the semi-autonomous city.
Police in Hong Kong made around 300 arrests as thousands of people took to the streets on Wednesday to voice anger over national security legislation proposed by China, that has raised international alarm over freedoms in the city.
In the heart of the financial district, riot police fired pepper pellets to disperse a crowd, and elsewhere in the city police rounded up groups of dozens of suspected protesters, making them sit on sidewalks before searching their belongings.
A heavy police presence around the Legislative Council deterred protesters planning to disrupt the debate of a bill that would criminalise disrespect of the Chinese national anthem.
The bill is expected to become law next month.
Angry over perceived threats to the semi-autonomous city's freedoms, people of all ages took to the streets, some dressed in black, some wearing office clothes or school uniforms and some hiding their faces beneath open umbrellas in scenes reminiscent of the unrest that shook Hong Kong last year.
"Although you’re afraid inside your heart, you need to speak out," said Chang, 29, a clerk and protester dressed in black with a helmet respirator and goggles in her backpack.
Many shops, banks and offices closed early.
The latest protests follow the Chinese government's proposal for national security legislation aimed at tackling secession, subversion and terrorism in Hong Kong.
The planned laws could see Chinese intelligence agencies set up bases in Hong Kong.
The United States, Britain, the European Union and others have expressed concern about the legislation, widely seen as a possible turning point for China's freest city and one of the world's main financial hubs.
But Chinese authorities and the Beijing-backed government in Hong Kong say there is no threat to the city's high degree of autonomy and the new security law would be tightly focused.
China responded by saying it would take necessary countermeasures to any foreign interference.
Asian shares slipped over the rising tension between the United States and China. Hong Kong's bourse led declines with a 0.46 percent drop.
The background of violence
The bill makes it illegal to insult or abuse the "March of the Volunteers." Those found guilty could face up to three years in prison and a maximum fine of $6,450.
The anthem bill was first proposed in January 2019, after Hong Kong spectators jeered at the anthem during high-profile, international soccer matches in 2015.
Anti-China sentiment has been on the rise in Hong Kong since 2014 protests, known as the Umbrella Revolution, that stemmed from the Chinese government’s decision to allow direct election of the city leader only after it screened candidates.
In the end, the plan for direct elections was dropped.
The debate over the bill also comes as Beijing moves to enact a national security law for Hong Kong, aimed at forbidding secessionist and subversive activity, as well as foreign interference and terrorism, after a months-long anti-government protest movement last year that at times resulted in violent clashes between police and protesters.
Critics say that the national anthem bill is a blow to freedom of expression in the city, while Beijing officials previously said that the law would foster a patriotic spirit and the country’s socialist core values.