“I’m going to do everything I can to save him,” Trump told Fox News Radio in an interview. “We’ll see what we can do … we’re going to do everything we can.”

Lai, 77, has pleaded not guilty to charges under Hong Kong’s national security law of conspiracy to collude with foreign forces, as well as to a separate charge of conspiracy to publish seditious material. He has been held in solitary confinement for more than 1,500 days since December 2020.

Liu Pengyu, the spokesperson for China’s embassy in Washington, said Lai had been “a key orchestrator and participant in anti-China, destabilising activities in Hong Kong.”

“We strongly oppose external forces using judicial cases as a pretext to interfere in China’s internal affairs or to smear and undermine Hong Kong’s rule of law,” he said.

Trump has said he would raise Lai’s case as part of negotiations with China over trade and tariffs.

On Monday, the US and China extended a tariff truce for another 90 days, staving off triple-digit duties on each other’s goods.

On Tuesday, US treasury secretary Scott Bessent said trade officials from the two sides will meet again within the next two or three months to discuss the future of the economic relationship.