Beijing’s national security law for Hong Kong will not damage the city’s autonomy or freedoms, Chinese Foreign Minister Wang Yi said on Sunday, as protesters and police clashed on the streets of the former British colony over what many see as a crushing blow to its pro-democracy movement.

The proposed legislation was aimed only at a “very narrow category of acts that seriously jeopardise national security”, such as “treason, secession, sedition or subversion”, he told a press conference at the ongoing National People’s Congress (NPC) in Beijing.

The law would have “no impact on Hong Kong’s high degree of autonomy, the rights and freedoms of Hong Kong residents, or the legitimate rights and interests of foreign investors in Hong Kong”, Wang said.

“Instead of becoming unnecessarily worried, people should have more confidence in Hong Kong’s future. This will improve Hong Kong’s legal system and bring more stability, a stronger rule of law and a better business environment to Hong Kong.”

Beijing’s decision to table a resolution on the national security law at its annual parliamentary session as anti-government protests – sparked by now-shelved plans to introduce an extradition law – was widely condemned in Hong Kong and overseas. Opposition lawmakers in the city said it would be the death of the “one country, two systems” model that allows Hong Kong a high degree of autonomy compared to cities in mainland China.

The draft legislation references Article 23 of the Basic Law – Hong Kong’s mini-constitution – that the city must enact its own laws to prohibit acts of treason, secession, sedition and subversion against Beijing.

It also states that “relevant national security organs” from the Chinese central government will set up agencies in Hong Kong to “fulfil relevant duties to safeguard national security” in Hong Kong when needed.

Beijing has effectively bypassed Hong Kong’s legislature by having the law promulgated – put into effect automatically – by listing it in Annex III of the Basic Law, in line with Article 18 of the mini-constitution.

Wang said that while Beijing had authorised Hong Kong to fulfil its constitutional responsibility to enact national security laws under Article 23, that “does not prevent the central government from establishing a legal system and enforcement mechanisms for safeguarding national security”.

Critics, however, have said that enacting the law through promulgation means there is no room left for negotiation on how the bill is drafted.

“The central government holds the primary and ultimate responsibility for national security in all subnational administrative regions,” Wang said. “This is the basic theory and practice underpinning national sovereignty and common practice in countries around the globe.”

The national security bill was a “pressing priority” for the city, as the protests that began last summer had led to “escalating violence and terrorist activities” from Hong Kong independence organisations and localists, as well as “excessive unlawful foreign meddling”.

Beijing has repeatedly claimed that the protests in Hong Kong have received foreign backing, including from the US, but has never provided any evidence to support the allegations.

“All this has placed national security in serious jeopardy and posed a grave threat to Hong Kong’s prosperity and stability, and the practice of ‘one country, two systems’,” Wang said.

“Under such circumstances, establishing a legal enforcement mechanism for safeguarding national security in the Hong Kong SAR [special administrative region] has become a pressing priority. We must get it done without the slightest delay.”

Thousands of people took to the streets of Hong Kong on Sunday to protest against the national security law, and were met with riot police armed with tear gas, pepper spray and water cannons.