More than 1,000 protesters staged a sit-in outside Hong Kong's Legislative Council late Saturday after lawmakers approved a controversial 8.6-billion-dollar high-speed railway project.

The group surrounded the council building and refused to let transport chief Eva Cheng and other government officials leave after lawmakers voted in favour of the project at the end of an eight-hour meeting.

"Withdraw the proposal. Eva Cheng, shame on you!" the protesters, mostly students and young professionals, chanted as hundreds of policemen looked on.

Cheng was in her car in the council's carpark for about an hour before she was forced to return to the building, with protesters refusing to leave.

"Nobody can represent our voice. So we came here tonight to make our voice heard," Henry Lam, 24, told AFP.

Police earlier used pepper spray on some of the protesters as they tried to break through a barricade.

The council meeting was the third held to discuss funding approval for the project, which will link Hong Kong and Guangzhou, capital of neighbouring Guangdong province.

The Guangzhou-Shenzhen-Hong Kong Rail Link will form part of China's national high-speed rail network and allow people to travel from Hong Kong to Guangzhou in 48 minutes, just under half the current duration of the journey.

Officials say the project is important for fostering economic ties between Hong Kong and major cities on the Chinese mainland and hope construction will be completed by around 2015.

"The project has been through a 10-year consultation... It is an important investment," Cheng said after the meeting.

Pro-democracy legislators tried to delay the decision, saying the public had not been properly consulted and that the scheme was over-priced.

They also said it would benefit only developers while forcing villagers along the route to relocate.

Protesters said the project received the green light only because the election system allows the majority of the Legislative Council seats to be filled by pro-government politicians.

At present, only half of Hong Kong's legislature is directly elected while a largely pro-Beijing committee effectively controls the selection of the remainder and appoints the city's chief executive.

More than 1,000 protesters staged a sit-in outside the official residence of Hong Kong's Chief Executive Donald Tsang late Friday to urge the government to drop the project.