A Hong Kong court today disqualified two pro-independence lawmakers from taking office, ruling their oath of allegiance invalid in a judgment in step with Beijing, which last week intervened in the city's legal system.

But Judge Thomas Au said he would have made the ruling anyway, without the controversial intervention by China's parliament.

Beijing ruled that Hong Kong legislators must swear allegiance to Hong Kong as part of China, adding that candidates who take the oath of office in an insincere manner will be disqualified and not given another chance to swear in.

Democratically elected legislators Yau Wai-ching, 25, and Baggio Leung, 30, sparked controversy when they displayed a banner declaring 'Hong Kong is not China' and substituted derogatory terms for 'China' while taking their oaths last month.

Au placed an injunction on the two acting as legislators.

"With or without the interpretation (by Beijing), the court would reach the same conclusion," Au said in the 56-page judgment.

The pair have yet to announce whether or not they will appeal.

Hong Kong, a former British colony, returned to China in 1997 under a "one country, two systems" agreement that ensured its freedoms and wide-ranging autonomy, including a separate legal system.

But Communist Party rulers in Beijing have ultimate control and some Hong Kong people are concerned they are increasingly interfering to head off dissent.

Demonstrators angry at Beijing clashed with riot police last week, unfurling umbrellas to block pepper spray in scenes reminiscent of the 2014 pro-democracy protests dubbed the 'Umbrella Movement'.

About 2,000 members of Hong Kong's legal community marched in silence later in the week to protest against what they called a "severe blow" to the city's judicial independence.

But tens of thousands of government supporters over the weekend rallied against the promotion of Hong Kong independence, a topic once taboo but becoming increasingly mainstream since the 2014 street protests failed to stop Beijing from vetting candidates for the city's leadership elections.

Beijing's decision represents some of the worst privately held fears of senior judges and some government officials in Hong Kong, according to sources close to them.

Chinese officials in public and private comments have said talk of separatism, including advocacy for self-determination, is not to be tolerated.

Apart from the Leung and Yau, at least four lawmakers in the 70-member Legislative Council support various degrees of greater autonomy for Hong Kong.

They collectively received one in five votes in September's city-wide election, though the pair's popularity has slumped since the oath-taking controversy.

- Reuters