Beijing has said its leaders will not discuss the bill during the summit, which begins Friday in Osaka, Japan.
Protesters, meanwhile, surrounded police headquarters in Hong Kong in another public display of frustrations.
Earlier, hundreds of people moved through the city streets to stop at consulates, including the United States, to deliver letters calling for foreign governments to address their concerns at the annual G-20 summit.
Carrie Lam, Hong Kong’s pro-Beijing chief executive, has suspended the extradition bill, which would allow for case-by-case transfers to mainland China. But Lam has not fully withdrawn the measure.
Many believe the bill would be a huge blow to the “one country, two systems” framework enacted in 1997 when the semiautonomous state was handed back from Britain to China.
The political crisis has tanked Lam’s approval ratings, according to a survey released Tuesday by the Public Opinion Program at the University of Hong Kong. The poll found Lam’s approval rating is 23 percent with a disapproval rate of 67 percent.
At a rally Wednesday night, thousands of demonstrators crowded into a park in central Hong Kong and spilled into nearby roadways calling for international support.
People held their mobile phones in the air singing “Do You Hear the People Sing?” from the musical “Les Misérables.”
“As world leaders meet at the G-20 Summit, Hong Kong citizens now urge all of you, including Xi Jinping, to answer our humble questions: Does Hong Kong deserve democracy? Should Hong Kong people enjoy democracy?” said a statement from the Civil Human Rights Front, organizers of Wednesday night’s event.
A crowdfunding campaign raised more than $860,000 to buy ads in major international newspapers warning of the threat that the extradition bill poises to Hong Kong residents.
Organizers of the ad campaign, calling themselves Freedom Hong Kong, said Wednesday evening that they had purchased large advertisements in major newspapers including the New York Times.
Later, hundreds of demonstrators surrounded the Hong Kong Police Force headquarters for the second time in less than a week, blocking entrance gates with metal barricades and walls of umbrellas. Some protesters spray-painted graffiti on police buildings, others shined strobe lights and lasers through the windows.
“Maybe the pressure from foreign governments can help Hong Kong,” said a protester who spoke on the condition of anonymity because of fear of reprisals from authorities. “I want them to save Hong Kong along with the Hong Kong people.”