Hong Kong leader CY Leung has urged protesters to back reforms set out by Beijing, amid huge pro-democracy rallies in the territory.
Speaking on the National Day holiday, Mr Leung said Hong Kong should work with Beijing to achieve progress.
The protesters want Beijing to withdraw plans to vet candidates for the next Hong Kong leadership election in 2017.
Activists say they expect the biggest crowds yet on the streets to coincide with the holiday.
Mr Leung, Hong Kong’s chief executive, has rejected campaigners’ calls for him to stand down. Chinese President Xi Jinping has reaffirmed Beijing’s control over the territory.
Early on Wednesday, Mr Leung attended a ceremony in Hong Kong marking National Day, which celebrates the founding of communist China in 1949.
The flag-raising ceremony went ahead peacefully, as student protesters looked on. The authorities have cancelled a fireworks display that was due to take place later in the day, however.
Addressing officials, Mr Leung said that while people had different ideas about what constituted a “desirable reform package”, it was better to have the right to vote than not.
“We hope that all sectors of the community will work with the government in a peaceful, lawful, rational and pragmatic manner to… make a big step forward in our constitutional development,” he said.
Beijing ruled last month that it would allow Hong Kong people to elect their next leader in 2017. But the choice of candidates will be restricted to those approved by a pro-Beijing committee – meaning the Chinese government can effectively screen candidates.
A rumbling protest campaign ballooned into mass street demonstrations at the weekend.
Police responded initially with tear gas and pepper spray, but riot police later withdrew and since early on Monday the situation has remained calm.
At least three key parts of the city are being blockaded by protesters, including the central business district.
Crowds swelled again on Tuesday night and the demonstrators – who include student groups, supporters of the Occupy Central movement and others angered by the police response – say they are confident of greater numbers on Wednesday.
“I think there will be a massive turnout, over 100,000 people tonight and leading into National Day,” Occupy Central activist Ed Chin told AFP news agency.
“We are not afraid of riot police…. We will not leave until Leung Chun-ying resigns,” student leader Lester Shum told the crowd.