A motorcyclist carrying a "Liberate Hong Kong" sign as he drove into police at a protest has become the first person charged with inciting separatism and terrorism under a new security law in Hong Kong.
Beijing imposed the legislation on the former British colony earlier this week despite protests from Hong Kongers and Western nations.
Critics say the law - which punishes crimes of secession, subversion, terrorism and collusion with foreign forces with up to life in prison - is aimed at crushing dissent and a long-running campaign for greater democracy.
Police say 23-year-old Tong Ying-kit rammed and injured some officers at an illegal protest on Wednesday. A video online showed a motorbike knocking over several officers on a narrow street before the driver falls over and is arrested.
Tong, who was hospitalised after the incident, was charged less than 24 hours after the city government said the slogan he was carrying - "Liberate Hong Kong, revolution of our times" - connotes separatism or subversion under the new law.
The rallying cry appears on placards, T-shirts, and post-it notes stuck to walls around Hong Kong.
China's parliament adopted the security law after sometimes violent protests last year triggered by fears Beijing was stifling freedoms, guaranteed by a "one country, two systems" formula agreed when Hong Kong returned to Chinese rule in 1997.
Authorities in Beijing and Hong Kong say the law aims at a few "troublemakers" and not wider rights that underpin the city's role as a gateway for capital flows in and out of China.
But international anxiety is growing after authorities arrested 10 people under the new law within 24 hours of it taking effect. The European Union (EU) has put Hong Kong high on its agenda while the United Nations' rights office expressed alarm over arrests.
'I'm not scared' - protester
At another court, dozens gathered in solidarity with a man charged for stabbing a policeman in the arm during Wednesday's disturbances. They held up blank pieces of paper to show fears for free speech.
"I'm not scared. Come what may," said a 25-year-old protester who gave his name only as Wilson.
On Wednesday's 23rd anniversary of Hong Kong's return to Chinese rule, police arrested about 370 people, with 10 cases involving violations of the new law.
In a further ominous sign for activists, a Communist Party cadre prominent during a 2011 clampdown on land rights protesters in a south China village is to head a newly-empowered national security office in Hong Kong, official news agency Xinhua said.
Zheng Yanxiong, 57, most recently served as secretary general of the Communist Party committee of Guangdong province, bordering Hong Kong.
Leaked footage during the 2011 dispute showed him berating villagers and calling foreign media "rotten".
The new legislation gives the security office greater enforcement action and powers to take suspects onto the mainland, as well as granting privileges for agents, including that Hong Kong authorities cannot inspect their vehicles.
Some activists have been keeping a low profile or leaving.
Demosisto, a pro-democracy group led by Joshua Wong, disbanded hours after the legislation was passed, while prominent group member Nathan Law left the city.
"The protests in Hong Kong have been a window for the world to recognise that China is getting more and more authoritarian," Law told Reuters.
Hong Kong's publicly-funded public broadcaster RTHK, which has felt the pressure of government scrutiny, appeared to take heed of the law, reproducing the slogan as "L*******#HongKong" in a comment on Twitter, to the scorn of some social media users.