A protest Sunday in Hong Kong against Beijing interference in the former British colony drew thousands of demonstrators wary of efforts by the central government to silence voices for independence.

Protesters carried signs in Chinese and English with themes such as "Stop annexation of HK democratic rights" and "Defend rule of law." Some protesters clashed with police, who used pepper spray to quell the disturbance. At least two arrests were made.

The protest focused on two pro-independence politicians — Sixtus Leung and Yau Wai-ching — who were elected to Hong Kong's Legislative Council in September. When they took their oaths of office last month, they deviated from the script designed to show allegiance to the Chinese government, using a derogatory pronunciation of China and making other disparaging gestures, the state-run Xinhua News Agency reported.

When a legislative clerk ruled the oaths invalid, the council president scheduled a redo. That's when Hong Kong's special administrator, handpicked by Beijing, stepped in to bar them from taking office at all.

The National People's Congress Standing Committee in Beijing has taken up the case. It has the power to interpret the "Basic Law," essentially a constitution negotiated for the city when it was returned to China in 1997.

A final ruling by Beijing could be issued Monday, but the committee's preliminary statement Saturday did not bode well for the duo. The statement noted that emerging advocacy of Hong Kong independence has resulted in some people displaying independence banners and establishing independence organizations.

"They have hit the bottom line of the 'one country, two systems' principle and posed a grave threat to national sovereignty and security," the statement said.

Yau, 25, and Leung, 30, represent a powerful push for freedom driven by Hong Kong's youth. Many of the pro-independence candidates took part in the Umbrella Revolution of 2014, when youthful protesters took to the streets to express anger over efforts by Beijing to prescreen candidates for office in Hong Kong.

Voters in Hong Kong further fueled the challenge to Beijing's authority in the September election, when pro-democracy candidates won about 40% of the legislature's 70 seats. That provided veto power over central government edicts.

The standing committee in Beijing said Saturday it can't ignore bold efforts by Yau, Leung and others to undermine the rule of law in Hong Kong, the statement said.

"If the situation is allowed to continue, the immediate interests of residents in (Hong Kong) and the development interests of the nation will be damaged," the statement said.