Hong Kong police have fired tear gas and water cannon to disperse thousands protesting against Beijing's plan to directly impose national security laws on the city, signalling a return to mass protests that roiled the financial hub last year.
Crowds on Sunday thronged the bustling shopping district of Causeway Bay, where echoes of "Hong Kong independence, the only way out," and other slogans rang through the streets.
A protester wearing a black hoodie and surgical mask held a banner that said: "I stand for Hong Kong's independence."
Calls for independence are anathema to China's Communist Party leaders, who say such a notion for the Chinese-ruled city is a "red line" that cannot be crossed.
The proposed new national security framework stresses Beijing's intent "to prevent, stop and punish" such acts.
The protest - the first since Beijing proposed national security laws on Thursday - poses a fresh challenge to Chinese President Xi Jinping as authorities struggle to tame public opposition to China's tightening grip over the global financial hub.
"I am worried that after the implementation of the national security law, they will go after those being charged before and the police will be further out of control," said Twinnie, 16, a secondary school student who declined to give her last name.
"I am afraid of being arrested but I still need to come out and protest for the future of Hong Kong."
The demonstrations come amid concerns over the fate of the "one country, two systems" formula that has governed Hong Kong since the former British colony's return to Chinese rule in 1997. The arrangement guarantees the city broad freedoms not seen on the mainland, including a free press and independent judiciary.
The city government sought on Sunday to reassure the public and foreign investors over the security laws, that have sent a chill through financial markets and drawn a rebuke from foreign governments, human rights groups and some business lobbies.
Police conducted stop-and-search operations in Causeway Bay and warned people not to violate a ban on gatherings of more than eight, imposed to curb the spread of coronavirus.
They said protesters hurled umbrellas, water bottles and other objects at them and they responded with tear gas "to stop the violent acts of rioters."
Some protesters used bins, traffic cones and other debris to set up road blocks, leaving key thoroughfares deserted. Police said more than 40 people were arrested.
China has dismissed other countries' complaints about the proposed legislation as "meddling," saying the proposed laws will not harm Hong Kong autonomy or foreign investors.
In a bold challenge to the mainland authorities, a small group of democracy activists protested outside Beijing's main representative office in the city, chanting, "National security law is destroying two systems."
"It's a moveable red line. In future they can arrest, lock up and silence anyone they want in the name of national security. We have to resist it," protester Avery Ng of the League for Social Democrats told Reuters.
The Chinese government's top diplomat said the proposed legislation would target a narrow category of acts and would have no impact on the city's freedoms nor the interests of foreign firms.
Last year's anti-government protests plunged the city into its biggest political crisis in decades, battered the economy and posed the gravest popular challenge to President Xi since he came to power in 2012.