The 77-year-old founder of the Apple Daily newspaper is charged with foreign collusion under Hong Kong's national security law, which Beijing imposed following huge and sometimes violent pro-democracy protests in 2019.

Closing arguments in the long-running trial were originally expected to begin Thursday, but all court sessions were suspended due to bad weather.

As court resumed Friday, defence lawyer Robert Pang told the court that Lai had heart "palpitations" and had experienced the feeling of "collapsing", but added that the tycoon didn't want attention to be concentrated on his health.

Lai has been kept behind bars since December 2020, reportedly in solitary confinement, and concerns have previously been raised over the septuagenarian's welfare.

Pang told AFP outside court the defence had requested that Lai be excused from the closing arguments, as he is not required to speak.

"(Lai) believes the episodes will occur when he is fatigued, and coming to court fatigues him," Pang said in court Friday.

Judge Esther Toh said Lai should not worry about disturbing the court and could always speak up if he was uncomfortable.

Prison-arranged medical staff had detected "no abnormality" with Lai's heart but had nevertheless arranged for a wearable heart monitor and medication, Toh said.

"I don't want anything to..." she said before trailing off.

Judge Alex Li said it would be "prudent" to begin proceedings on Monday after the arrangements were sorted.

- 'The world is watching' -

The sprawling trial, which began in December 2023, is entering its final stages as Western nations and rights groups continue to call for Lai's release.

Aside from the collusion offence -- which could land him in prison for life -- Lai is also charged with "seditious publication" related to 161 op-eds carrying his byline.

The Committee to Protect Journalists (CPJ) said Thursday that "the world is watching how Hong Kong treats its journalists".

US President Donald Trump told a Fox News radio programme on Thursday that he had previously brought up the Lai case with Chinese President Xi Jinping.

"I'm going to do everything I can to save him... you could also understand President Xi would not be exactly thrilled," the outlet quoted Trump as saying.

The Hong Kong government said Wednesday it "strongly disapproved and rejected the slanderous remarks made by external forces" regarding Lai's case.

Lai is a British citizen and his son Sebastien reiterated in March calls for the Keir Starmer administration to do more, saying: "I don't want my father to die in jail."

- 'Political prisoner' -

Lai has given spirited testimony over more than 50 days, fielding questions about his political ideology, management style and overseas contacts.

He described himself at least twice as a "political prisoner", which drew sharp rebukes from the three-judge panel.

Prosecutors showed the court a diagram titled "(Lai's) external political connections", arguing that he had exerted influence in the United States, Britain and Taiwan.

Lai has denied calling for sanctions against China and Hong Kong and said he never advocated separatism.

Apple Daily was forced to close in 2021 after police raids and the arrests of its senior editors.

A former Apple Daily employee surnamed Chang queued outside court on Friday to support Lai, describing him as a "caring" boss.

"His health worsened after he was taken into custody, but I think his spirit is strong, and I hope he can persist," Chang told AFP.