Police have raided a property northwest of Sydney as part of an operation to disrupt unauthorised protests by climate activists.

Officers were carrying an investigation at a property on Putty Road in Colo when they say a group of people approached them and attacked their vehicle about 8.30am on Sunday, police said.

“An unmarked police vehicle from nearby attended to provide the officers with assistance before they became surrounded by the group of people, who then damaged the vehicle tyres, preventing it from leaving,” NSW Police said in a statement.

“Nearby police resources attended to assist, where two people were arrested and the remainder of the group fled into bushland.”

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Police have since made further arrests with help from specialist units including PolAir, the dog unit, the public order and riot squad, and police rescue.

A crime scene has been established at the property and police expect the operation to continue throughout the day.

The operation was carried out at a camp occupied by members of climate activist group Blockade Australia, the Sydney Morning Herald reports.

Police are expected to provide a further update on Sunday.

-AAP