Starmer told lawmakers in parliament that Lai’s case was “a priority” for his Labour government and foreign secretary David Lammy had previously raised the issue with his Chinese counterpart.

“We do call for the Hong Kong authorities to release immediately our British national,” the UK premier said during his weekly question-and-answer session, agreeing with main opposition leader Rishi Sunak that the case against Lai was politically motivated.

Lammy is due to travel to China this week for talks in a rare diplomatic visit between the two countries, whose relations have been hit by a security crackdown in Hong Kong and human rights concerns.

Last week, Lai’s legal team told reporters in London that they hoped Lammy would put Lai’s case “front and centre” during his visit, which has not been confirmed officially.

Starmer did not contradict Sunak’s mention of the trip.

Sunak urged Lammy to also tell his counterpart in Beijing that Lai’s detention was a breach of the treaty underpinning Britain’s return of Hong Kong to China in 1997.

Lai, 76, is the founder of the now-shuttered popular Chinese-language tabloid Apple Daily, which supported mass pro-democracy protests in the economic hub.

Detained in 2020, he is awaiting trial on charges including colluding with foreign forces and sedition.

On Taiwan, which China claims, Starmer said huge military drills were “not conducive to peace and stability” in the Taiwan Strait, while he also called on Beijing to lift sanctions imposed on a string of UK lawmakers.

Hawkish MPs who have spoken out against China’s crackdown on freedoms in Hong Kong, alleged abuses of the Uyghur minority and claims of Chinese espionage and nefarious influence in the UK have found themselves sanctioned in recent years.