Thousands of people marched on Hong Kong's parliament on Sunday to demand the scrapping of proposed extradition rules that would allow people to be sent to mainland China for trial — a move which some fear puts the city's core freedoms at risk.

Opponents of the proposal fear further erosion of rights and legal protections in the free-wheeling financial hub — freedoms which were guaranteed under the city's handover from British colonial rule to Chinese sovereignty in 1997.

Early estimates suggested several thousand people had joined the march along Hong Kong Island from Causeway Bay to the council in the Admiralty business district.