Trump did not discuss a specific deal to free Lai but spoke more broadly about concerns surrounding the 77-year-old publishing mogul's health and well-being after his lengthy trial on national security charges, one of the people said.

Trump spent less than five minutes discussing the issue, the person added.

"President Trump brought up Jimmy Lai's case, just as he said he would," said the administration official. "Both President Trump and President Xi engaged in the discussion that followed."

"It was raised by Trump and noted by Xi," a third person said on condition of anonymity given the sensitivity of the leaders' meeting.

That person said Trump suggested that Lai's release would be good for US-China relations and beneficial for China's image.

Trump's direct intervention comes as Lai awaits a verdict after a trial widely seen as a symbol of China's crackdown on rights and freedoms in the Asian financial hub under a national security law imposed after mass pro-democracy protests in 2019.

Lai, who founded the now-shuttered pro-democracy Apple Daily tabloid newspaper, has pleaded not guilty to two charges of conspiracy to collude with foreign forces, and a charge of conspiracy to publish seditious material.

The US president said ahead of the talks that he planned to raise Lai's case but neither he nor both sides' readouts mentioned it afterwards.

The White House declined to comment on questions about Lai being discussed during the Trump-Xi meeting. It has not confirmed that Trump broached the issue.

Liu Pengyu, spokesperson for China's embassy in Washington, said he was not aware of details specific to Lai from the leaders' meeting, but stressed that Lai's "crimes have gravely undermined Hong Kong's prosperity and stability”.

"Any attempt to interfere with the judicial process or to undermine the rule of law in Hong Kong will not succeed," Liu said.

Chinese foreign ministry spokesperson Mao Ning told a regular press briefing in Beijing on Thursday that Lai was the "main planner and participant" in the "anti-China riots" in Hong Kong.

"The Chinese central government firmly supports the Hong Kong judiciary in performing its duties in accordance with the law," Mao said.

"Hong Kong affairs are China's internal affairs and brook no interference from external forces."

Though Lai is a British citizen, his case has been a source of friction between Washington and Beijing, with Trump having said last year during his campaign for the presidency that he would "100 percent" get Lai out of China.

Lai's son, Sebastien Lai, last week praised Trump and said he was "incredibly grateful" following earlier unconfirmed reports that Trump had raised his father's case with Xi.

"Knowing President Trump's reputation as the Liberator in Chief, I pray that his continued support and commitment will convince President Xi to free my father before it is too late," Sebastien Lai said in a statement.

Trump hailed the trade-dominated talks with Xi as a success, pointing also to progress on rare earth shipments and promises of "strong action" on the export of chemicals used to produce the highly addictive fentanyl drug. He said tensions over Taiwan never came up in the 90-minute talks in South Korea.

Lai has been held in solitary confinement for more than 1,700 days according to his family and rights groups.

Chinese and Hong Kong officials have previously said it is important the local legal process is able to take its course, and that Lai has been being given a fair hearing.

Hong Kong, a former British colony, operates a separate judicial system to the rest of China, based around Common Law traditions that mean Lai has greater legal protections than in mainland China.

Lai is now being held in the Lai Chi Kok prison as he awaits a verdict after his trial ended in late August, according to two people familiar with his situation. If convicted, he could face a maximum sentence of life imprisonment.

He is suffering from heart palpitations and has been provided with a heart monitor and medication, his lawyers said in court.