Prominent activist Nathan Law has left his native Hong Kong in a bid to avoid persecution under a sweeping national security law that Beijing imposed on the territory earlier this week.
Law said on Twitter early on Friday that he had chosen to continue his activism abroad over being kept silent or facing persecution at home.
He did not disclose his whereabouts, citing security risks.
"No Hong Konger is under the illusion that Beijing has any intention to respect our basic rights and honour its promises to us," Law wrote.
"Mass arrests have already begun on the first day of the National Security Law's implementation."
The law, enacted Tuesday, targets secession, subversion, terrorism and collusion with foreign forces in Hong Kong.
Law said his safety might already be in jeopardy after he criticised the law in a US congressional hearing he attended by live stream on Wednesday.
Law has lobbied the international community to take action against Beijing's increasing authority in Hong Kong, a former British colony that was promised autonomy from the Mainland until 2047.
His political party Demosisto announced their disbandment on Wednesday after leading members Joshua Wong and Agnes Chow stepped down citing risks to the group under the law.
"As the plane took off the runway, I gazed down at the skyline I love so much one last time," Law tweeted at the end of the thread announcing his departure.
"Should I have the fortune to ever return, I hope to still remain as I am: the same young man with these same beliefs. Glory to Hong Kong."
Australian Associated Press