China said Monday it would sanction US-based non-profits including the National Endowment for Democracy (NED) and Human Rights Watch in retaliation for the United States passing legislation in support of Hong Kong's protesters.

Foreign ministry spokeswoman Hua Chunying did not give details about the sanctions or articulate how the non-profits' operations will be affected in the semi-autonomous city, where many maintain regional offices to conduct China-related work.

China will also suspend rest-and-recuperation visits to Hong Kong by US military ships and aircraft, Ms Hua said, adding that China could take further retaliatory moves.

The comments were a stark warning towards organisations that China sees as aligned with Washington - and the opening salvo in what Beijing has promised to be “forceful” retaliation to the United States for the Hong Kong Human Rights and Democracy Act that was passed by Congress and signed into law by Donald Trump last week.

The move could further elevate Hong Kong as a flashpoint between Beijing and Washington. The Chinese government has viewed the five-month protests to be an American attempt to foment a colour revolution rather than an outpouring of genuine anger over police conduct and declining political freedoms.

Hong Kong protests: Latest after court strikes down face mask ban Show all 24 1 /24 Hong Kong protests: Latest after court strikes down face mask ban Hong Kong protests: Latest after court strikes down face mask ban Police in riot gear move through a cloud of smoke as they detain a protester at the Hong Kong Polytechnic University AP Hong Kong protests: Latest after court strikes down face mask ban A protester takes cover under an umbrella Reuters Hong Kong protests: Latest after court strikes down face mask ban A protestor reacts to police officers EPA Hong Kong protests: Latest after court strikes down face mask ban Pro-democracy protesters react after the police fired tear gas outside the Hong Kong Polytechnic University EPA Hong Kong protests: Latest after court strikes down face mask ban A pro-democracy protester holds a placard EPA Hong Kong protests: Latest after court strikes down face mask ban Protesters react as police fire tear gas AFP via Getty Hong Kong protests: Latest after court strikes down face mask ban An anti-government protester is silhouetted during protests Reuters Hong Kong protests: Latest after court strikes down face mask ban Tear gas engulf umbrellas Reuters Hong Kong protests: Latest after court strikes down face mask ban A protester lowers himself down a rope from a bridge to a highway, to escape AFP via Getty Hong Kong protests: Latest after court strikes down face mask ban People form a human chain to pass materials as they gather for a march towards Hong Kong Polytechnic University AFP via Getty Hong Kong protests: Latest after court strikes down face mask ban Protesters are seen after leaving the campus of the Hong Kong Polytechnic University Reuters Hong Kong protests: Latest after court strikes down face mask ban Pro-democracy protesters during clashes with police outside the Hong Kong Polytechnic University EPA Hong Kong protests: Latest after court strikes down face mask ban Police spray blue-dyed liquid AP Hong Kong protests: Latest after court strikes down face mask ban Protesters are sprayed with blue liquid from water cannon during clashes with police outside Hong Kong Polytechnic University (PolyU) in Hong Kong, China, November 17, 2019. REUTERS/Tyrone Siu TYRONE SIU Reuters Hong Kong protests: Latest after court strikes down face mask ban Police officers detain a protester AP Hong Kong protests: Latest after court strikes down face mask ban An injured protester is evacuated by ambulance EPA Hong Kong protests: Latest after court strikes down face mask ban Injured people are taken away after clashes Getty Hong Kong protests: Latest after court strikes down face mask ban A protester throws back a tear gas canister fired by police at the Hong Kong Polytechnic University in Hong Kong on November 17, 2019. - Hong Kong police fired tear gas on November 17 morning at protesters intent on keeping their stranglehold on a major tunnel as pro-democracy activists vowed to "squeeze the economy" into next week. (Photo by Ye Aung Thu / AFP) (Photo by YE AUNG THU/AFP via Getty Images) YE AUNG THU AFP via Getty Hong Kong protests: Latest after court strikes down face mask ban Police arrest anti-government protesters Getty Hong Kong protests: Latest after court strikes down face mask ban A protester's umbrella is seen on fire during clashes with police outside Hong Kong Polytechnic University (PolyU) in Hong Kong, China November 17, 2019. REUTERS/Athit Perawongmetha ATHIT PERAWONGMETHA Reuters Hong Kong protests: Latest after court strikes down face mask ban Medical staff carry a protester out of the campus of Hong Kong Polytechnic University Reuters Hong Kong protests: Latest after court strikes down face mask ban Protesters try to extinguish a tear gas canister Reuters Hong Kong protests: Latest after court strikes down face mask ban Protesters take a rope down from a bridge to a highway, to escape from Hong Kong Polytechnic University campus AFP via Getty Hong Kong protests: Latest after court strikes down face mask ban A protestor gestures during a confrontation with police AP

Organisations including NED, Human Rights Watch, Freedom House, the National Democratic Institute for International Affairs and International Republican Institute, will be sanctioned for their “odious behaviour” in Hong Kong, where they have “strongly instigated extremely violent criminal activities”, Ms Hua told reporters in Beijing.

“They bear great responsibility for the current chaos in Hong Kong,” she said. “These organisations deserve to be sanctioned and they must pay the price for it.”

China, echoing governments including Venezuela and Egypt, has previously taken aim at NED, a group established in 1983 and funded by Congress to promote democracy worldwide. The foreign ministry in August distributed a lengthy report that named the NED as a US intelligence front and listed its history of funding political groups in Hong Kong going back 20 years.

It is not immediately clear how the sanctions would affect foundations or corporations that donate to the blacklisted non-profits. Few of the groups have staff on China's mainland.

Foreign non-profit workers inside China have long faced suspicion and a degree of vulnerability. Michael Kovrig, a former Canadian diplomat working for the Crisis Group NGO who has been detained for the past year on national security grounds, was seized in the midst of a diplomatic dispute between Beijing and Ottawa.

Peter Dahlin, a Swede, was detained in 2016 for his involvement in providing legal aid to a network of Chinese activists that the Communist Party considered subversive.

China has elevated scrutiny of foreign non-profits since the passage of an NGO law in 2017 that gave security officials broad supervision powers.

Last week, Chinese officials disclosed for the first time a police investigation conducted under the 2017 NGO law. The New York-based non-profit Asia Catalyst, which worked on HIV-related public health projects in southern China, was investigated by Beijing police and fined, the foreign ministry announced.

No employees were arrested, a person familiar with the matter said.