Last week, China enacted a security law outlawing four national security crimes: subversion, secession, terrorism and colluding with foreign forces.
Hong Kong has released additional details of China's sweeping new national security law for the former British colony.
The announcement said security forces had overriding authority to enter and search properties for evidence and stop people from leaving the city.
Hong Kong returned to China on July 1, 1997, under a "one country, two systems" formula guaranteeing wide-ranging autonomy and freedoms not enjoyed on the mainland, including an independent judiciary.
But under China's new legislation, crimes of secession and sedition will be punishable by up to life in prison, stoking concerns of a much more authoritarian era in a city which has been racked by anti-China protests for the past year.
Last week China enacted a security law outlawing four national security crimes: subversion, secession, terrorism and colluding with foreign forces.
US diplomat in Hong Kong says security law use a 'tragedy'
The top American diplomat in Hong Kong said that it is a “tragedy” to use the new national security law to chip away at freedoms in the Asian financial hub.
“Using the national security law to erode fundamental freedoms and to create an atmosphere of coercion and self-censorship is a tragedy for Hong Kong,” Hanscom Smith, US consul general to Hong Kong and Macau, told reporters.
“Hong Kong has been successful precisely because of its openness and we’ll do everything we can to maintain that."
Any activities such as shouting slogans or holding up banners and flags calling for the city’s independence are a violation of the law regardless of whether violence is used. The maximum penalty is life imprisonment.
Critics see it as Beijing’s boldest step yet to erase the legal firewall between the former British colony and the mainland’s authoritarian Communist Party system.
Since the law went into effect, the government has specified that the popular protest slogan “Liberate Hong Kong, revolution of our time” has separatist connotations and is thus criminalised.
In Hong Kong’s public libraries, books by pro-democracy figures have been pulled from the shelves, including those written by prominent pro-democracy activist Joshua Wong and politician Tanya Chan. The authority that runs the libraries said it is reviewing the books in light of the new legislation.
Activist Wong says world must 'stand with Hong Kong'
The world must stand in solidarity with Hong Kongers after Beijing imposed the new security law, activist Wong said on Monday, vowing to continue campaigning for democracy.
Wong, one of the city's most prominent young activists, was speaking outside a court where he and fellow campaigners were being prosecuted for involvement in civil unrest which rocked Hong Kong last year.
Ahead of a court appearance on Tuesday, Wong, 23, remained unbowed.
"We still have to let the world know that now is the time to stand with Hong Kong," he told reporters, adding that China could not "ignore and silence the voice of Hong Kong people."
China rebukes UK over Hong Kong 'gross interference'
China's ambassador to London accused Britain on Monday of gross interference and making irresponsible remarks over Beijing's imposition of the new security legislation that he said could damage future Chinese investment.
Britain has described the law as a "clear and serious" violation of the 1984 Joint Declaration under which it handed back its colony to China 13 years later and said that London would offer around 3 million residents a path to British citizenship.
"The UK government keeps making irresponsible remarks on Hong Kong affairs," Ambassador Liu Xiaoming told reporters in the strongest rebuke Beijing has issued to London since Britain criticised the security law.
On the British offer to give British National (Overseas) (BNO) passport holders in Hong Kong a path to British citizenship, he said, "This move constitutes gross interference in China's internal affairs and openly tramples on the basic norms governing international relations."
He said China would decide on its response after seeing how Britain proceeded with its passport offer.
Although Prime Minister Boris Johnson describes himself as a "Sinophile," he has also spoken of the need to "stick up for our friends in Hong Kong," straining relations with Beijing.
He has also toughened his language on a provisional decision to allow China's Huawei to be involved in the development of Britain's 5G infrastructure, saying he would protect critical infrastructure from "hostile state vendors."
Johnson has faced intense pressure from the United States and some British lawmakers to ban the telecommunications equipment maker on security grounds and Britain's media minister said on Monday the Huawei decision was not set in stone.
Liu said that, although China wanted friendly relations with Britain, there might be many consequences if Britain treated Beijing as an enemy or with suspicion.
China issues Canada travel warning
China issued a travel warning for Canada on Monday and said bilateral relations could deteriorate further over Ottawa's response to the new law imposed in Hong Kong.
Canada last week suspended its extradition treaty with Hong Kong and halted exports of sensitive military gear to the financial hub as Western nations voiced concern about the legislation's impact on the city's special rights.
"China strongly condemns this and reserves the right to make further response. All consequences arising therefrom will be borne by Canada," Foreign Ministry spokesman Zhao Lijian said at a regular briefing.
The Chinese embassy in Ottawa separately issued the travel warning, urging its citizens to remain cautious because of "frequent violent actions by law enforcement agencies in Canada, which have triggered many demonstrations."
Canada updated its travel advisory for Hong Kong so Canadians will know how the law might affect them.