China's top legislative body has ruled that Hong Kong politicians advocating independence are ineligible to hold public office, effectively barring two young rebel lawmakers.
It is Beijing's most direct intervention in the territory's judiciary since the 1997 handover from British rule and is likely to stoke further unrest on Hong Kong's streets.
Protests in Hong Kong over Chinese intervention
Police clash with protesters who rallied in the streets of Hong Kong to denounce Beijing's interpretation of an article in Hong Kong's constitution, known as the Basic Law.
Thousands protested overnight on Sunday, angered by moves to block newly-elected pro-independence legislators Yau Wai-Ching, 25, and Sixtus "Baggio" Leung, 30, from retaking their oaths.
Their oaths, made during a parliamentary swearing-in ceremony last month, were voided after the pair deliberately inserted a derogatory term for China while displaying a banner reading "Hong Kong is not China".
In Beijing on Monday, the National People's Congress Standing Committee issued a detailed interpretation of Hong Kong's Basic Law – the territory's de facto constitution – stating that people who deliberately altered the words of the oath or delivered it in a "dishonest manner" will be barred from office. It said the interpretation was "timely and necessary" amid growing pro-independence activity in the city.
"The interpretation demonstrates the central government's firm determination and will in opposing 'Hong Kong independence','' China's Hong Kong and Macau Affairs Office said in a statement Monday, according to official news agency Xinhua.
It is only the second time China has issued an interpretation without express request from Hong Kong's government or courts since regaining sovereignty over the territory. It is unprecedented, however, in that it effectively overrides a pending decision from local courts over whether Ms Yau and Mr Leung should be allowed to retake their oaths, undermining the city's semi-autonomy and independent judiciary.
Hong Kong's leader, chief executive Leung Chun-ying (above), said Beijing had been careful in exercising its prerogative.
"The NPCSC would not interpret the Basic Law if there was no need for it," Mr Leung told reporters in Hong Kong on Monday.
Four people were arrested in Sunday's overnight protests as hundreds clashed with police. The scenes were reminiscent of the citywide pro-democracy demonstrations two years ago that raged for 79 days and stemmed from concerns over creeping Communist Party influence.
Ms Yau and Mr Leung gained prominence following the 2014 protests, along with other more radical political voices advocating for greater scepticism toward – or even independence from – mainland China.
Under the banner of new independence-leaning political party Youngspiration, the two were swept into office in September's Legislative Council elections on the back of strong support from young Hong Kong voters who feel increasingly disenfranchised by mainland China.
Speaking to reporters in Beijing on Monday, the Communist Party's Basic Law committee chair Li Fei suggested Hong Kong's younger generation had been "incited" by "sinister" forces who had long sought to subvert and overthrow Communist Party rule.
In comments full of references to how Hong Kong suffered under Japanese occupation during World War II, Mr Li said "the Chinese have a good patriotic tradition: all spies and traitors come to no good end".
"Thus, I think, if one continues to support those who betray their country and nation entering LegCo to conduct activities of splitting the state … then I think their standpoint is the standpoint of the Fascists of that time."