The UK must be "bold" in standing up for the freedom and autonomy of Hong Kong, says Benedict Rogers, East Asia Team Leader at Christian Solidarity Worldwide.
Writing on ConservativeHome, Mr Rogers said Hong Kong had become the "new frontline in the battle between freedom and repression" in the wake of protests against the extradition Bill that would see certain criminals tried in mainland China.
Hundreds of thousands of Hong Kongers have marched through the city in protest againt the Bill, which chief executive Carrie Lam has refrained from withdrawing completely.
Mr Rogers said Britain must strengthen its support for the people of Hong Kong "at this critical time in what has been one of Asia's freest and most open cities, and a major international centre, but whose basic freedoms are threatened as never before".
The protests took an alarming turn in the past week when a group of men in masks and white shirts attacked protesters at an MTR station in Yuen Long, a town in the New Territories.
Hong Kong locals have blamed the attacks on Triad gangsters, whom they accuse of being hired hands. The strength of feeling was evident in a counter-protest held in the town on Saturday against the MTR station incident.
Mr Rogers, who is founder of the pro-democracy campaign group Hong Kong Watch, urged Britain's new foreign secretary Dominic Raab to make Hong Kong a priority.
"I urge Raab to send a clear message that Britain will stand up for Hong Kong's freedoms and autonomy promised under the 'one country, two systems' principle," he said.
Mr Rogers spoke more broadly of his concerns for the rights of religious minorities in China and warned against any partnership with Chinese technology giant Huawei.
"And I urge him to be bold in reviewing Britain's relationship with China, recognising that we want to continue to do business with such a major economy but not at the cost of our values," he said.
"China must be challenged on the mass atrocities it is perpetrating against the Uyghurs and other Muslims in Xinjiang, the most severe crackdown on Christianity since the Cultural Revolution, the continuing persecution of Tibetans and Falun Gong, allegations of forced organ harvesting from prisoners of conscience as concluded by the recent China Tribunal chaired by the lawyer who prosecuted Slobodan Milosevic, Sir Geoffrey Nice, QC, not to mention the threats China poses to our own freedoms and national security.
He added: "I hope he will confer with the new Education Secretary over the dangers of Huawei investment in 5G technology."