Several foreign governments have criticized the new law, which gives China broad powers to crack down on political crimes in the territory.
In an escalation of tensions with China, Britain on Monday suspended an extradition treaty with Hong Kong to protest a new security law that gives China sweeping powers and is seen by critics as imperiling basic freedoms in the former British colony.
The move, announced in Parliament by Dominic Raab, the foreign secretary, was prompted directly by fears that anyone extradited to Hong Kong from Britain could be sent on to mainland China with ease.
Mr. Raab also announced an extension to Hong Kong of a longstanding arms embargo against China that has been in force since 1989.
Both measures underscore a hardening stance among British politicians — across the political spectrum — over China’s treatment of Hong Kong, a former colony that returned to Chinese control in 1997, and 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 Mike Pompeo, the United States secretary of state, to London for a two-day visit. China is expected to be high on the agenda, and consensus on a tough posture looks likely.
Hours before Mr. Pompeo was scheduled to arrive in Britain, Mr. Raab told lawmakers that the extradition treaty would be suspended immediately and indefinitely, and would not be reintroduced “unless and until there are clear safeguards.”
“The U. K. is watching and the whole world is watching,” added Mr. Raab added.
The extension to Hong Kong of the arms embargo, Mr. Raab said, would include the ban of potentially lethal weapons, their components or ammunition, or “any equipment — not already banned — which might be used for internal repression.”
Shackles, intercept equipment, firearms and smoke grenades would be covered by the embargo, Mr. Raab added, describing the British move as part of a proportionate response to China’s failure to observe its international obligations.
The measures were 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 introduced after months of pro-democracy demonstrations.
