China enacted a new security law in June on Hong Kong, which allows the country to extradite political opponents and curbs freedoms in the former British colony. The new law has sparked outrage from allies of Hong Kong, with UK Prime Minister Boris Johnson committing to allowing three million passport holders in the area to immigrate to the UK. Mr Lai owns the Apple Daily newspaper, and is a pro-democracy activists.
The Hong Kong and Macau Affairs Office has called for exemplary punishment for Mr Lai to deter further unrest in the city.
The government body also claimed Mr Lai conspired with foreign agents and poses a danger to national security.
Mr Lai was arrested along with two of his sons and seven others on charges of fraud and colluding with foreign agents.
If Mr Lai is convicted of the charges, he could be jailed for life.
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The arrest has sparked uproar in Hong Kong, with residents in the city showing their support for the billionaire.
Half a million extra copies of Apple Daily were sold yesterday after Mr Lai’s arrest.
The Hong Kong tabloid published an image of Mr Lai in handcuffs as its front page, and vowed to keep fighting.
Protestors in the city also rallied in shopping centres, holding copies of the tabloid, and were confronted by police enforcing the new security law.
Mr Lai was believed to run a fundraising group the Global Times alleged lobbied foreign governments for sanctions on Hong Kong.
As he was being arrested, he said: “Of course press freedom is hindered, needless to say.”
But Hu Xijin, editor-in-chief of the state-owned Global Times, suggested that complaints by the US government about Mr Lai’s arrest were proof that he was its top agent in the territory.
He added: “He’s become a 100 percent traitor.”
China’s Foreign Ministry followed the arrest with sanctions on US senators.
But most senators dismissed the move, with Marco Rubio mocking Beijing’s attack.
He said: “Last month China banned me. Today they sanctioned me.
“I don’t want to be paranoid but I am starting to think they don’t like me.”