The son of jailed Hong Kong media tycoon Jimmy Lai has implored Donald Trump to secure his father’s release from prison during a historic state visit to China next week.

Mr Lai, the 78-year-old founder of Apple Daily, the city’s most vocal pro-democracy newspaper, was sentenced to 20 years in prison in February on disputed collusion and sedition charges, as part of a mounting national security crackdown on the former British colony by Beijing.

He has reportedly been kept in solitary confinement since his December 2020 arrest, despite mounting concerns for his deteriorating physical health.

Sebastien Lai told The Independent that he “held hope” that Hong Kong would “act rationally and release my father” if the US president presses the issue during meetings with Chinese leader Xi Jinping which are reported to be taking place next week.

Mr Trump pledged during his 2024 campaign to secure his release and earlier this week vowed to bring up the case on his trip to Beijing.

The younger Mr Lai lauded Mr Trump’s record as “an incredible negotiator” and “one of the best deal makers” in his appeal.

“That’s why we have so much hope on his visit,” he said. “This is a case he genuinely, from my understanding, cares about and he’s someone who’s an incredible negotiator. So hopefully I’ll get to see my father again.”

He separately urged the British government to make his father’s release a precondition for resetting relationships with Beijing, lamenting that “had the government done more three, four years ago, who knows?”

Mr Trump’s visit to China on 14-15 May will be the first for a US president in nearly a decade. The two leaders are expected to discuss a raft of issues, including Mr Lai’s detention and the war in Iran. The US president raised the case during a summit with Mr Xi in South Korea’s Busan last year.

Ahead of the trip, a bipartisan group of more than 100 US lawmakers, including some two-thirds of the Senate, signed a letter urging Mr Trump to seek the release of Mr Lai. A copy of the letter seen by the Washington Post read: “Your direct engagement is critical to securing Mr Lai’s immediate release on humanitarian parole, so he can receive appropriate medical care and reunite with his family.”

Sebastien Lai told The Independent: “I think as countries that believe in democracy and freedom, it’s important to push the Hong Kong and Chinese governments in the right direction … It’s about saving [Jimmy Lai’s] life.”

“It’s a very easy way for [Mr Xi] to show good faith to the American people and to show good faith to us, to the UK … Of all these big geopolitical things, this is a very easy one to ask.

“It’s well within their ability to release my father and directly beneficial to Hong Kong and China as well,” he added, saying it seemed “mind-boggling that they are so determined to torture him like this”.

Announcing their verdict in February, three judges said Mr Lai’s offences fell within the harshest penalty tier for those of a “grave nature”, accusing him of being the driving force behind persistent foreign conspiracies. The sentence drew uproar from the British government and other democracies around the world.

Lawyers for the elder Mr Lai told the BBC in March that he had decided not to appeal against his conviction. They did not say why and declined to comment further.

His son told The Independent: “From what I understand, my father decided not to appeal. I think anybody looking at the trial can see the reason why. It’s essentially a stacked deck. He hasn’t received a fair trial in any of his sentencing and this is not just my opinion … this is a pretty black-and-white type of thing.

“So in this situation, what’s the point of appealing? … This isn’t rational. They’re out to get him.”

Mr Lai was concerned about his father’s ailing health, still held in isolation in Hong Kong’s maximum-security Stanley Prison. Jimmy Lai suffers from diabetes and heart problems, and his health has declined dramatically in custody, supporters say.

His son said information has been more scarce, with his sister, Claire, campaigning and unable to visit him in prison.

“He’s still in solitary confinement. I get less information from him now,” he said. “I could write to him. I think he writes back, but I don’t get as much health information from him now.

“I think many people would be very depressed in this situation, but he still keeps hope … He still keeps fighting and it’s very moving.

”It gives us a lot of courage as well because even though they’ve taken so much of his health, so much of his physical belongings, they haven’t broken his spirit.”

Britain raised its concerns for Mr Lai during Sir Keir Starmer’s visit to China in January. But just days later, Mr Lai, a British citizen, was handed down a staggering 20-year sentence.

The younger Mr Lai urged Britain to make the resetting of relations with Beijing conditional on his father’s release.

He said: “If we want to reset relationships with them, the least they [China] could do is release a 78-year-old British citizen from jail.

“I don’t see how there’s warming in relationships without this happening as a precondition to this warming in relationships.”

He did acknowledge that this UK government seems to have taken the case “more seriously”.

“When I started this, it was a few governments ago, but it was an absolutely horrible time when they weren’t even calling for his release. And obviously my dad’s not out yet, but had they done more three or four years ago, who knows what might have happened? But it does seem like this government is keen to do this.”

The UK Foreign Office was approached for comment.

In her most recent comments on the case in February, foreign secretary Yvette Cooper said Mr Lai’s sentencing was “tantamount to a life sentence”.

She said that the British government would “rapidly engage further” on the case.

“We stand with the people of Hong Kong, and will always honour the historical commitments made under the legally binding Sino-British Joint Declaration. China must do the same.”