BEIJING — China’s top legislative body on Sunday struck a blow to democracy advocates in Hong Kong, ruling that Beijing can effectively veto candidates it deems undesirable from seeking the region’s top leadership job in a 2017 election.

The decision makes it virtually certain that Hong Kong will soon have large-scale protests and acts of civil disobedience that will disrupt one of China’s crucial hubs for trade and banking.

“The democrats will simply have to go to the streets now,” said Michael Davis, a law professor at the University of Hong Kong. Beijing’s leaders, he said are “offering the kind of democracy where they get to vet the candidates, and that is unacceptable to a lot of people here.”

Since it was reunited with China in 1997, Hong Kong has enjoyed a semi-autonomous status, with freedoms of assembly and speech that residents on the mainland can only dream about. But China’s recent actions towards the former British colony have alarmed many.

At issue is Beijing’s interpretation of Hong Kong’s “Basic Law,” a type of constitution that resulted from Great Britain’s decision to return the territory to China in 1984. The basic law includes language granting Hong Kong a “high degree” of autonomy, including the ability of residents to elect their chief executive in 2017.

Activists want groups and political parties in Hong Kong to be free to nominate their own candidates. Beijing officials and state media have said for months that would lead to chaos and is in violation of the Basic Law.