Hong Kong pro-democracy media tycoon Jimmy Lai
The trial of Hong Kong pro-democracy media tycoon Jimmy Lai is being closely watched as a barometer of Hong Kong's political freedoms and judicial independence. AFP

Hong Kong pro-democracy tycoon Jimmy Lai pleaded not guilty Tuesday to "sedition" and "collusion" charges in a high-profile national security trial that could see him jailed for life.

The charges against Lai -- founder of the now-shuttered popular Chinese-language tabloid Apple Daily -- revolve around the newspaper's publications, which supported pro-democracy protests and criticised Beijing's leadership.

Lai, 76, is also accused of collusion via calling for international sanctions against Chinese and Hong Kong officials.

"Not guilty," Lai said in English for each of the three charges read out.

Wearing a white shirt and a navy blue jacket, the septuagenarian was surrounded by three prison guards in the defendant's dock.

He wore headphones to help him hear the trial more clearly, according to his lawyer.

Lai's trial, which began in late 2023 after he was jailed for more than 1,100 days, is being closely watched as a barometer of Hong Kong's political freedoms and judicial independence.

Other defendants in the case include three Apple Daily companies that have been taken over by the Hong Kong government, six former executives of the newspaper, and two young activists related to an advocacy group called Stand With Hong Kong Fight For Freedom (SWHK).

"This case is about a radical political figure... who conspired with others to bring into hatred and stir up opposition to the government of (Hong Kong) and the central authorities and to collude with foreign countries or external elements to endanger national security," lead prosecutor Anthony Chau told the court Tuesday.

Chau called Lai "the mastermind" who used his media business "as a platform to pursue his political agenda... and orchestrated a conspiracy with the so-called democracy and freedom advocacy group Stand with Hong Kong Fight for Freedom".

The prosecution cited 161 publications of Apple Daily between April 2019 and the newspaper's last day in June 2021 as "examples of seditious publications... with a view to polluting the minds of the impressionable ones".

Lai was also accused of providing instructions and financial support for SWHK to lobby foreign countries for sanctions, including the United States, the UK, New Zealand, Australia, Japan, Czech Republic, Portugal and Ireland.

He was originally charged with one count of "conspiracy to produce seditious publications", two counts of "conspiracy to collude with foreign forces to endanger national security" and one count of "collusion".

The latter two offences carry up to life in jail under the security law Beijing imposed in 2020 to quell dissent after the huge democracy protests the year before.

Prosecutors told the court Tuesday they will not pursue the standalone "collusion" charge as it formed part of Lai's "conspiracy to collusion" charge.