China’s parliament has passed national security legislation for Hong Kong, setting the stage for the most radical changes to the former British colony’s way of life since it returned to Chinese rule almost exactly 23 years ago.

Cable TV, citing an unidentified source, said on Tuesday the law was passed unanimously by the Standing Committee of China’s National People’s Congress.

The legislation pushes Beijing further along a collision course with the US, Britain and other Western governments, which have said it erodes the high degree of autonomy the global financial hub was granted at its July 1, 1997, handover.

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In response to the legislation, the US began eliminating Hong Kong’s special status under American law on Monday, halting defence exports and restricting the territory’s access to high technology products.

Hong Kong leader Carrie Lam, speaking at her regular weekly news conference, said it was not appropriate for her to comment on the legislation as the meeting in Beijing was still ongoing.

A draft of the law has yet to be published. Beijing says the law, which comes in response to 2019’s often-violent pro-democracy protests in Hong Kong, aims to tackle subversion, terrorism, separatism and collusion with foreign forces.

This month, China’s official state agency Xinhua unveiled some of its provisions, including that it would supersede existing Hong Kong legislation and that the power of interpretation belongs to the Chinese parliament’s top decision-making body, the National People’s Congress Standing Committee.

Beijing is expected to set up a national security office in Hong Kong to “supervise, guide and support” the city government. Beijing could also exercise jurisdiction on certain cases.

It is still unclear which specific activities are to be made illegal, how precisely they are defined or what punishment they carry.

The South China Morning Post, quoting an unnamed source, said Xinhua would publish details of the law on Tuesday afternoon and Hong Kong officials would gather at Beijing’s top representative office in the city later for a meeting on the legislation.

Authorities in Beijing and Hong Kong have repeatedly said the legislation is aimed at a few “troublemakers” and will not affect rights and freedoms, nor investor interests.

The law comes into force as soon as it is gazetted in Hong Kong, which is thought to be imminent.

Police banned this year’s July 1 rally on the anniversary of the 1997 handover, citing coronavirus restrictions. It is unclear if attending the rally anyway would constitute a national security crime if the law came into force by Wednesday.

The South China Morning Post, citing “police insiders”, said about 4000 officers would be on stand by on Wednesday to handle any unrest if people defy the ban.