The daughter of Jimmy Lai, the pro-დემოკრატი oligarch who was imprisoned in Hong Kong, is concerned about her father's deteriorating health in prison, saying that his nails "sometimes fall off" and his teeth are rotting.

Lai, 78, has been imprisoned since December 2020 and faces a possible life sentence. Earlier this month, he was found guilty of conspiracy with foreign powers under Hong Kong's controversial national security law (NSL).

Chinese authorities have denied that Lai has been mistreated in prison, saying he is "in good health".

The BBC has seen a letter written by Lai's family to UK Prime Minister Rishi Sunak, urging him to secure Lai's release when he meets Chinese President Xi Jinping next month.

His daughter, Clare Lai, who is in exile in London, told the BBC that she fears "she may never see him again".

"Of course, I'm worried that my father will become a martyr, and I don't want him to become a martyr. But I wouldn't be here today, I wouldn't be speaking, if I didn't think this was his best chance to be reunited with his family."

She described her father as "an extremely strong and powerful man" when he entered prison, but has "lost a significant amount of weight" over the past year.

"He's diabetic, he has heart problems that he's never had before. His nails are turning purple-grey and sometimes fall off. His teeth are rotting."

"He has back and leg pains. Some days it's painful for him to stand. Sometimes he can't stand. And some days he can't even get out of bed."

Lai's family has repeatedly expressed concerns about his deteriorating health. Lai's son, Sebastian, told the BBC earlier this year that his father's "body is breaking down".

A spokesperson for the Chinese Foreign Ministry's Office in Hong Kong said earlier this month that Lai's "legal rights and interests have been fully protected" and he is "in good health".

They added that "a lawful, humane, appropriate and healthy custody environment" has been provided to Lai.

Lai, a British citizen, is the most prominent person to be charged under the NSL, which was introduced in 2020 in response to massive pro-democracy protests in Hong Kong.

Beijing defends the law as necessary to maintain stability in Hong Kong, but critics say it has effectively banned dissent.

Lai was charged with lobbying foreign governments to impose sanctions on Hong Kong and China. He was also found guilty of sedition under a colonial-era law published in his now-defunct Apple Daily newspaper.

Following Lai's sentencing earlier this month, the UK condemned it as "politically motivated persecution" and said it "targeted... the peaceful exercise of freedom of expression".

"The UK has repeatedly called for the abolition of the national security law and the end of the prosecution of all those charged under it", the Foreign, Commonwealth & Development Office said.

In their statement earlier this month, the Chinese authorities said Western efforts to "influence court verdicts through political pressure are clearly in breach of the spirit of the rule of law and fully expose their hypocritical "double standards" that the Chinese side strongly opposes."

Starmer's visit to China in late January 2026 will be the first by a UK Prime Minister since 2018.