China's top legislature on Monday effectively barred two democratically elected separatist lawmakers from taking office in Hong Kong, an intervention into a local political dispute that's likely to spark further turmoil in the southern Chinese city.

The National People's Congress Standing Committee in Beijing issued a ruling on a section of Hong Kong's mini-constitution covering oaths taken by officials. It acted after a provocative display of anti-China sentiment by two newly elected pro-independence Hong Kong lawmakers at their swearing-in ceremony last month.

Hong Kong's government will fully implement the interpretation, said Chief Executive Leung Chun-ying, the Beijing-backed leader of the semiautonomous Chinese region.

Thousands of protesters took to Hong Kong streets on Sunday after Beijing signaled it was planning to intervene. They demanded that China's central government stay out of the political dispute, saying the move would undermine the city's considerable autonomy and independent judiciary by bypassing the top court, where the case is currently being heard.

Police used pepper spray and batons against some demonstrators trying to reach Beijing's liaison office after the rally ended. Four people were arrested while two officers were injured, police said.

In the interpretation published Monday, the top legislative panel in Beijing said talk of independence for Hong Kong is intended to "divide the country" and severely harms the country's unity, territorial sovereignty and national security.

The interpretation involves an article in Hong Kong's mini-constitution, known as the Basic Law, that covers oaths taken by lawmakers.

The dispute centers on two newly elected pro-independence lawmakers, Sixtus Leung, 30, and Yau Wai-ching, 25, who altered their oaths to insert a disparaging Japanese expression for China. Displaying a flag reading "Hong Kong is not China," they vowed to defend the "Hong Kong nation." Their oaths were ruled invalid, but subsequent attempts have resulted in mayhem in the legislature's weekly sessions.

Beijing's interpretation said that those who advocate for independence for Hong Kong are not only disqualified from election and from assuming posts as lawmakers but should also be investigated for their legal obligations.

At a briefing with reporters in Beijing, Li Fei, a deputy secretary general of the NPC Standing Committee, denied that the central government was escalating its interference in Hong Kong's affairs.

Hong Kong's Basic Law stipulates that Beijing holds the legal power to make interpretations, and it is the central government's duty to step in when there is a difference of legal opinion, Li said. He also warned that promoting independence was not a matter of freedom of speech.

"Breaking 'one-country two-systems' is violating the law, not voicing a political view," said Li, referring to a principle under which Beijing is supposed to let Hong Kong keep its capitalist economic and political system separate from mainland China's until 2047.

The central government's stance is absolute, he added: "There will be no leniency."

Leung told a packed news briefing in Hong Kong that the Youngspiration duo "deliberately violated the oath taking procedure, and content requirements of the oath.

"They even insulted the country and the Chinese people in their words and deeds in the oath taking as well as advocating Hong Kong independence. Their conduct has caused widespread indignation in Hong Kong and across the country."

Beijing officials struck a similar note in the closing moments of the Monday briefing, which took an unexpected turn as Li, the standing committee official, revived the accusation that the oath-takers had intentionally used a Japanese term to smear the Chinese people.

Li decried the duo as "traitors" and recounted Japanese World War II atrocities in Hong Kong in graphic detail, telling of nurses raped and bodies bayoneted and tossed into the Hong Kong harbor.

"I hope the people of Hong Kong won't forget the history of Japanese invaders," he said. "All the traitors who sell out the country never have good endings."

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Chan reported from Hong Kong. Associated Press journalists Gillian Wong in Beijing and Josie Wong in Hong Kong contributed to this report.