Hundreds of protesters have occupied Hong Kong’s parliament building for hours after breaking away from a protest on the anniversary of the state’s transfer of sovereignty to China from Britain.

Police firing tear gas have moved in to evict protesters from the Legislative Council (LegCo) building.

At midnight, local time, hundreds of police charged towards the building after warning protesters to clear it.

The incident follows weeks of unrest in Hong Kong over a controversial extradition law.

Hundreds of thousands took part in the earlier protest – the latest rally against a proposed law that critics fear could be used to extradite political dissidents to mainland China.

Dozens of demonstrators smashed their way through the glass facade of LegCo. They were joined inside by hundreds more after police vacated the building during the evening.

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Inside the building, protesters defaced the emblem of Hong Kong in the central chamber, raised the old British colonial flag, spray-painted messages across the walls, and shattered furniture.

They clad in plastic helmets and brandishing umbrellas retreated from a baton charge by riot police, who quickly overcame the makeshift barriers in front of the building.

Inside, diehard demonstrators were pulled forcibly outside by their fellow occupants in an attempt to completely clear the building.

Democratic lawmakers Ted Hui and Roy Kwong stood in front of police asking them to allow protesters time to leave the area, the South China Morning Post reported.

Within an hour, the streets around the parliament building were clear of everyone except the media and police.

However, no arrests have yet been reported.