HONG KONG — Authorities in Hong Kong on Monday took an unprecedented step against separatist voices by banning a political party that advocates independence for the southern Chinese territory on national security grounds.

John Lee, the territory's secretary for security, announced that the Hong Kong National Party will be prohibited from operation from Monday.

Lee told reporters that the two-year-old group was prepared to use "all methods" to forge independence, which posed a threat to national security and broke the Basic Law, the mini-constitution that governs Hong Kong's relations with China.

"It has a clear agenda in making Hong Kong a republic," Lee said.

Lee also said the group had spread "hatred and discrimination against mainland Chinese."

Hong Kong's security bureau previously said in a letter to the National Party's leader, 28-year-old Andy Chan, that the party should be dissolved "in the interests of national security or public safety, public order or the protection of the rights and freedoms of others."

The ban is likely to raise further questions about Beijing's growing influence in the former British colony, which was promised semi-autonomy as part of the 1997 handover. Chinese President Xi Jinping and other officials have warned separatist activity would not be tolerated.

Hong Kong is governed under a "one country, two systems" principle which allows the global financial hub a high degree of autonomy and freedoms not enjoyed in China, including an independent legal system and freedoms of speech and assembly.

The perception that Beijing is reneging on its promise of semi-autonomy and eroding Hong Kong's free elections and freedom of speech is helping fuel a rising generation of young activists calling for greater autonomy, if not outright independence.

Huge pro-democracy protests erupted in 2014 in response to the decision by China's ruling Communist Party to retain the right to effectively pre-screen candidates for Hong Kong's leadership.

Andy Chan is the leader of the pro-independence Hong Kong National Party. Anthony Wallace / AFP - Getty Images file

Chan, the National Party leader, told the Associated Press in July that police approached him with documents detailing his speeches and activities since the party's formation in 2016.

"I will never stop in my pursuit of freedom, human rights, equality and dignity," Chan told Reuters before Lee announced that the party was being outlawed.

The party was founded in response to frustration about Beijing's treatment of Hong Kong. Despite a promise of autonomy, activists complain mainland influence over its democratic elections is increasing.

Chan and other pro-independence candidates were disqualified from 2016 elections to the Hong Kong legislature after they refused to sign a pledge saying Hong Kong is an inalienable part of China. The Hong Kong National Party has never held any seats on the council.