Police lobbed canisters of teargas into the crowd yesterday evening after spending hours holding the protesters at bay.
The searing fumes sent protesters fleeing down the road.
Authorities launched their crackdown after the protest spiralled into an extraordinary scene of chaos as the crowd jammed a busy road and clashed with officers wielding pepper spray.
The protesters were trying to reach a mass sit-in being held outside government headquarters to demand Beijing grant genuine democratic reforms to the former British colony.
The protest is organised by the Hong Kong Federation of Students, which appealed for students to retreat following fears that police could use rubber bullets to disperse the crowd.
A co-organiser of Occupy Central, Chan Kin-man, says he supported the students’ decision.
Police said in a statement that they had arrested 78 people yesterday on charges of “forcible entry into government premises, unlawful assembly, disorderly conduct in public place, assaulting public officers and obstructing police officers in due execution of duties”.
More than 70 people were arrested on Saturday, including prominent student activist leader Joshua Wong, who has since been released.
Occupy Central had originally planned to paralyse the central business district on Wednesday, but organisers advanced the protest and changed the location in an apparent bid to harness momentum from student protests outside the government complex.
A statement by the movement said Hong Kong Chief Executive CY Leung had “failed to deliver on political reform”.
Mr Leung said the demonstration was “illegal” and elections would go ahead as planned.
But he said he and his government had “been listening attentively to members of [the] public”.