LONDON: Hong Kong activist Nathan Law said he had arrived in London after fleeing the former British colony where China has imposed a security law.
"With my backpack and small luggage in hand, I boarded my night flight. I had no idea what future awaited me. Only one thing seemed certain. My destination: London," Law said on Twitter.
"There's always one message I have: Hong Kongers will never give up. We aren't fractured. On the contrary, we're well-equipped to face the next difficult battle."
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Law told Reuters earlier this month that the rest of the world should stand up to President Xi Jinping and start to put human rights above financial gain.
One of Hong Kong's most prominent young activists, Law announced on Thursday he had fled overseas.
He was founding member of Demosisto, a party that disbanded earlier last week in response to the security law.
The party campaigned for democracy and for Hong Kongers to have a greater say in how the city is run but they did not advocate independence.
Nevertheless, Law and other prominent party members like former student leader Joshua Wong were vilified by Beijing, often described as "black hands" and separatists who conspired with foreigners to undermine China.
He and Wong both became household names as student leaders during protests in 2014.
READ: 'Hidden language': Hong Kongers get creative against security law
Law had shouted a slogan in a video message to a US Congress committee on Wednesday - "Liberate Hong Kong, Revolution of our Times" - a clarion call for protesters over the last year, chanted by huge crowds and plastered on banners.
For some it represents genuine aspirations to split Hong Kong from China. But for many others it is more a cry for democracy and expression of rising frustration with Beijing's rule.
In a statement, Hong Kong's government said the phrase was now illegal because it "contains the indications of Hong Kong independence, or alienating Hong Kong from China, or changing its legal status, or subverting the state".
On Wednesday, the first arrests were made under the legislation, mainly for protesters found in possession of pro-independence flags or stickers.