Hong Kong media are reporting that China has approved a contentious law that would allow authorities to crack down on subversive and secessionist activity.

The South China Morning Post newspaper and public broadcaster RTHK, both citing unnamed sources, said that the Standing Committee of the National People’s Congress voted unanimously to approve a national security law for Hong Kong on Tuesday.

There was no official confirmation from the central government in Beijing or Hong Kong officials.

Hong Kong leader Carrie Lam declined to comment on the law at a weekly meeting with reporters, saying it was inappropriate for her to do so while the Standing Committee was still meeting.

Hong Kong China Security Law
Pro-China supporters holding Chinese national flags, toast during a rally to celebrate the approval of a national security law for Hong Kong (Kin Cheung/AP)

She did say that once the law is passed, “the Hong Kong government will announce it and promulgate it for implementation here, and then I and my senior officials will do our best to respond to everyone’s questions, especially regarding the enforcement of this national law.”

The legislation is aimed at curbing subversive, secessionist and terrorist activities, as well as foreign intervention in the city’s affairs.

It follows months of anti-government protests that at times descended into violence in Hong Kong last year.

The law has met with strong opposition within Hong Kong and condemnation from former colonial ruler Britain, the US, the European Union and others.

Human rights groups have warned the law could target opposition politicians seen as insufficiently loyal to Beijing for arrest or disqualification from running in September elections for the Legislative Council.

Ahead of the announcement, the US government said on Monday it will bar defence exports to Hong Kong and will soon require licenses for the sale of items to Hong Kong that have both civilian and military uses.

The administration has warned for weeks that if the law was passed, it would take action to end special US trade and commercial preferences Hong Kong had enjoyed since reverting to Chinese rule in 1997.

“The United States is forced to take this action to protect US national security,” Secretary of State Mike Pompeo said in a statement.

“We can no longer distinguish between the export of controlled items to Hong Kong or to mainland China. We cannot risk these items falling into the hands of the People’s Liberation Army, whose primary purpose is to uphold the dictatorship of the (ruling Communist Party) by any means necessary.”

China Hong Kong Security Law
There are concerns the law would be used to curb opposition voices in the semi-autonomous territory (Andy Wong/AP)

The US Senate on Thursday unanimously approved a bill to impose sanctions on businesses and individuals — including the police — that undermine Hong Kong’s autonomy or restrict freedoms promised to the city’s residents.

Britain says it could offer residency and possible citizenship to around 3 million of Hong Kong’s 7.5 million people.

China has denounced all such moves as gross interference in its internal affairs and foreign ministry spokesperson Zhao Lijian on Monday said Beijing has decided to retaliate with visa restrictions on “US personnel who perform badly on Hong Kong related issues”.

China decided to use the National People’s Congress to enact the legislation after opposition within Hong Kong’s Legislative Council and within society as a whole made it impossible to pass at the local level.

The law is seen as the most significant erosion to date of Hong Kong’s British-style rule of law and high degree of autonomy that China promised Hong Kong would enjoy at least through 2047 under the “one country, two systems” framework.

Passage of the legislation will also allow the central government in Beijing to set up a national security office in Hong Kong to collect and analyse intelligence and deal with criminal cases related to national security.