China said on Thursday it is considering countermeasures against Britain and the United States for their policies targeting Hong Kong in the wake of Beijing's imposition of a national security law in the territory.

Chinese Foreign Ministry spokesman Zhao Lijian said in response to the British government's announcement that it will facilitate citizenship applications for British National (Overseas) passport holders in Hong Kong that Britain will bear consequences for breaking its promise.

"All Chinese compatriots in Hong Kong, including those holding BNO passports, are Chinese nationals," Zhao told reporters at a regular briefing in Beijing. "Before Hong Kong's handover, the British side had clearly promised not to give right of abode to BNO travel document holders."

Britain announced the policy change on the day the national security law was imposed in Hong Kong, the former British colony that returned to Chinese rule 23 years ago, allowing some 3 million BNO passport holders to live and work in Britain for five years, and to obtain a year-long settled status before applying for citizenship.

BNO passport holders were not granted the right of abode in Britain.

Zhao said Britain's insistence providing the passport holders a path for residency and citizenship while neglecting China's stern position is a serious violation of international law and the basic principle of international relations.

"China expresses strong condemnation and reserves the rights to take further actions, Britain should bear all consequences deriving," Zhao said, but he declined to comment on the action to be taken or when, saying "the time has not yet arrived."

Police officers keep watch on demonstrators in Hong Kong on July 1, 2020, who are staging a protest march against Beijing's controversial national security law for the former British colony that came into force the previous day. (Kyodo)

On the U.S. threat of sanctions against individuals and entities deemed responsible for eroding Hong Kong's autonomy, Zhao said the latter's plot to deter China from imposing the law in Hong Kong are doomed to fail.

"Stop in any way interfering with Hong Kong affairs, stop the legislative process and don't sign and implement the discouraging bill pertaining to Hong Kong, or the Chinese side will take firm and strong anti-measures while the U.S. side will bear all consequences," he said.

The U.S. House of Representatives passed the bill Wednesday, which, similar to a measure passed by the Senate last week, would have to be approved by the Senate before going to President Donald Trump for a signature.

Despite a police ban, thousands of protesters rallied in Hong Kong on Wednesday to demonstrate against the national security law. Police made about 370 arrests, including 10 people alleged to have breached the national security law.

Other than Britain and the United States, Australia also said it is considering to offer a safe haven for Hong Kong people.

"If you asking are we prepared to step up and provide support, the answer is yes," Prime Minister Scott Morrison told reporters at a press briefing, while urging China to uphold its prior commitments to Britain and to Hong Kongers.

"We are considering very actively the proposals that I asked to be brought forward several weeks ago and the final touches would be put on those and they'll soon be considered by Cabinet," he said.

In response, China's Zhao urged Australia to stop interfering in China's internal affairs with regard to Hong Kong issues and "not to wander further on the wrong path."

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