LONDON — In an escalation of tensions with China, Britain on Monday suspended an extradition treaty with Hong Kong in protest of a new security law that gives China sweeping powers and is seen by critics as a significant threat to basic freedoms in the British former colony.

The decision, announced in Parliament by Dominic Raab, the foreign secretary, was prompted by fears that anyone extradited to Hong Kong from Britain could be sent on to mainland China with ease.

But the measure also underscored a hardening stance among British politicians over China’s treatment of Hong Kong, a former British colony that returned to Chinese control in 1997, and the growing worries about more assertive behavior by Beijing on the global stage.

The announcement came as Prime Minister Boris Johnson of Britain prepared to welcome Secretary of State Mike Pompeo to London for a two-day visit during which China is expected to be high on the agenda.

Even before Britain announced the decision Monday afternoon, the measure was met with condemnation in China. Asked about the issue, a spokesman for the Chinese Foreign Ministry, Wang Wenbin, urged Britain to “stop going further down the wrong path.”

Britain is one of a growing number of countries to have denounced the security law in Hong Kong, which was brought forward after months of pro-democracy demonstrations and suddenly transformed the city by criminalizing secession, subversion and collusion with foreign forces. In response, Britain has also offered a pathway to citizenship for many Hong Kong residents should they feel pressured to leave the city.


Under that plan, 350,000 people who hold British National (Overseas) passports — and a further 2.5 million who are eligible for them — would be granted 12-month renewable visas that would allow them to work in Britain with the possibility of eventual citizenship.

Chinese anger over that move deepened last week when the British government reversed a decision to allow Huawei, a Chinese technology company, to play a role in establishing Britain’s 5G high-speed wireless network.

The United States had put Britain under pressure to exclude Huawei and, through its own measures against the Chinese technology firm, forced the British government to rethink its initial decision to allow Huawei to participate. Under the decision, British 5G providers will not be able to buy Huawei products after the end of the year, and will have to remove the company’s technology completely by 2027.