The 77-year-old British citizen and founder of the now-shuttered tabloid Apple Daily has been behind bars in Hong Kong since 2020, charged with foreign collusion.

Closing arguments in the long-running trial were originally expected to begin Thursday, but all court sessions were suspended by heavy rain.

As court resumed Friday, defence lawyer Robert Pang said Lai was experiencing heart "palpitations" and felt like he was "collapsing".

Lai's lawyers have requested he be excused from the closing arguments, as he is not required to speak.

"Coming to court fatigues him," Pang said.

Judge Esther Toh said prison-arranged medical staff had detected "no abnormality" with Lai's heart but would supply a wearable monitor and medication.

Judge Alex Lee said it would be "prudent" to begin proceedings on Monday after sorting the medical situation.

- 'The world is watching' -

If convicted, Lai faces up to life in prison under a national security law Beijing imposed on the semi-autonomous financial hub in 2020.

The law effectively quashed dissent following massive, and at times violent, democracy demonstrations in 2019.

In the years since the passage of the law, as well as an additional homegrown security act, most of the city's opposition lawmakers and democracy activists have either been jailed or fled abroad.

Lai, who was a child sweatshop worker before going on to found a clothing and then media empire, openly backed Hong Kong's democracy movement, earning the ire of China's state media.

His foreign collusion trial, which began in December 2023, is entering its final stages, with Western nations and rights groups continuing to call for his release.

In addition to collusion, Lai is also charged with "seditious publication" related to 161 op-eds published under his byline.

The Committee to Protect Journalists 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 brought up the tycoon's 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.

As Lai is a British citizen, his son Sebastien has called on Keir Starmer's administration to do more, saying: "I don't want my father to die in jail."

- 'Political prisoner' -

Lai has given spirited testimony, 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 closed 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.