Lai, who owns the Apply Daily, one of Hong Kong’s most-read newspapers, is one of the most prominent figures to be detained under a wider crackdown on political dissidents.
Lai was released on bail early Wednesday. Speaking to the BBC after his release, he said his arrest was “just the beginning.”
"When I was in custody I could not sleep,” Lai said. “I was thinking, if I knew that was going to happen to me now, [with] even more hardship [on the way], would I have done the same thing?
Lai said he has no regrets in his actions but warned young protesters to be “more cautious in our resistance to preserve our rule of law and freedom.”
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"We have to be more careful and creative in [our] resistance... we can't be as radical as before -- especially young people -- because the more radical [we are] the shorter lifespan we have in our fighting,” Lai said. "We have to really use our brain and patience, because this is a long fight."
Lai’s arrest has galvanized pro-democracy activists. On Tuesday, scores lined up at newsstands across the city to buy that same paper, handing over 10 Hong Kong dollars ($1.25) a copy in a bid to help the Apple Daily — and press freedom — survive.
Police have expanded their use of the law since it took effect six weeks ago, first arresting protesters with slogans deemed to be in violation and then activists over online posts.
The Apple Daily, known for its celebrity coverage as well as its condemnation of China's authoritarian rule, remained defiant, printing 350,000 copies — five times its usual print run — after police investigators left Next Digital and told employees they could go back to work.
The Associated Press contributed to this report.