Lai, who turned 78 this week, 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.

The founder of the Apple Daily newspaper has been behind bars since late 2020, reportedly in solitary confinement.

Journalists had already started queuing on Friday outside the West Kowloon courthouse for a place in the chamber where Lai's verdict will be read.

The hearing, before a three-judge panel, will begin at 10 am (0200 GMT) on Monday, according to a court diary notice seen Friday.

Previous hearings for Lai's case often drew a crowd of supporters and press, some of whom had to watch a livestream of proceedings elsewhere in the court building as they could not fit into the courtroom.

Aside from the collusion offence -- which could land him in prison for life -- Lai is also charged with "seditious publication", with prosecutors citing 161 items including op-eds with Lai's byline.

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

- 'Sham' -

The sprawling trial, which began in December 2023, has drawn criticism from Western nations and rights groups, who have called for Lai's release.

The Reporters Without Borders (RSF) group expressed outrage on Friday at the "short notice announcement" of the verdict, condemning the trial as "arbitrary and unlawful".

"The trial can only be described as a sham and has nothing to do with the rule of law," the group said in a statement, calling on Britain and the United States to press Beijing for his release.

The Committee to Protect Journalists (CPJ) called the trial "a travesty of justice".

"His national security trial was originally expected to last 30 days when it started in December 2023, after multiple delays. It has gone on for two years now," Beh Lih Yi, CPJ's Asia-Pacific regional director, told AFP.

She stressed "serious concerns that the 78-year-old may die in prison as each day passes".

Hong Kong authorities have rejected criticism related to Lai, saying his case was "handled strictly on the basis of evidence and in accordance with the law".

- Health concerns -

Chinese foreign ministry spokesman Guo Jiakun told a regular news conference on Friday that Beijing "firmly supports" Hong Kong in "safeguarding national security in accordance with the law and punishing criminal acts that endanger national security".

Throughout the trial, Lai has fielded questions about his political ideology, management style and overseas contacts.

He described himself at least twice as a "political prisoner", drawing rebukes from judges.

He has also denied calling for sanctions against China and Hong Kong, and said he never advocated separatism or violent resistance.

"The core values of Apple Daily are actually the core values of the people of Hong Kong... (including) rule of law, freedom, pursuit of democracy, freedom of speech, freedom of religion, freedom of assembly," Lai said in his testimony.

Lai is a British citizen, and his relatives voiced new concerns this month over the mogul's health.

"His nails turn almost purple, grey and greenish before they fall off, and his teeth are getting rotten," his daughter Claire Lai told AFP on a visit to Washington, where the family sought to rally support for her father.

The Hong Kong government said last week that prison authorities "handle the custodial arrangements for (Lai) in the same way as other persons-in-custody" and that he was "receiving appropriate treatment and care in prison".