HONG KONG -- Local authorities formally outlawed a Hong Kong independence group Monday as Chinese President Xi Jinping puts pressure on sovereignty movements in the name of national security.

The Hong Kong National Party became the first political organization to be banned in the territory since Britain returned its former colony to China in 1997.

The ban was enacted "in the interest of national security, public safety, public order and the protection of rights and freedoms of others," John Lee, the city's secretary for security, said Monday.

The order can be appealed, but it is unlikely to be overturned. Gatherings and donations for the party are now illegal, with a maximum punishment of three years in prison.

The National Party was founded in 2016 by Andy Chan, an activist in the mass protests of Hong Kong's 2014 Umbrella Movement that sought more democratic elections for the city's chief executive. The party's views promoting independence from mainland China have drawn support from some local youth.

The party held no seats in the city's Legislative Council and wielded little practical influence. But Hong Kong authorities enacted the ban anyway, apparently with Beijing's will in mind. China's Foreign Ministry openly opposed Chan being permitted to speak at the Hong Kong Foreign Correspondents' Club last month.

Hong Kong technically operates under the "one country, two systems" principle, which grants more autonomy and political freedoms than allowed in mainland cities. But Beijing is applying greater pressure on Hong Kong's democracy and independence groups.

China's cabinet, known as the State Council, said Monday through its Hong Kong and Macao Affairs Office that no independence movement can be tolerated, even if it does not use violent means, state-run Xinhua News Agency reported. When Xi visited Hong Kong in July 2017, he said that any attempt to challenge the central government's power "crosses a red line."

Members of Demosisto, a party founded by student leaders of the pro-democracy movement, are prohibited from running in elections for the city's legislature, and a leading figure of a "localist" independence group was jailed in June.

Claudia Mo and other pro-democracy lawmakers said Monday that the ban is intended to apply pressure on freedom of speech and assembly in Hong Kong. Concerns are growing that political activity will wither, with other groups also expected to be outlawed. The Umbrella Movement's struggles already have led many of the city's youth to distance themselves from political issues and focus on economic ties with the mainland.