Police have removed several protesters who chained themselves up outside office buildings in Collins Street in Melbourne's CBD as part of their call for greater action on climate change.

A group of up to 200 protesters — including anti-nuclear, anti-coal, climate change activists and Indigenous land rights campaigners — blocked an area between Russell and Swanston streets, outside BHP Billiton and Westpac at about 10:00am.

Charlie Wood, a protester at the scene, said those activists chained up had been told by police they would be arrested if they did not move.

She said she joined the demonstration to call on big business to do more to prevent climate change.

"Until we address the broken economic system that is perpetuating environmental and social injustice we're not going to solve climate change," she said.

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Onlookers said the crowd cheered as Victoria Police officers cut the protesters free.

BHP security teams were also on patrol outside the building and the front entrance to the building was, for a time, blocked off to the company's employees.

Environmental activist Jacynta Fuamatu said she wanted to highlight climate change issues in the Pacific.

"A lot of Pacific representatives in Paris at the moment are making sure their stories are being heard about the impacts of climate change in front line communities," she said.

"For me I have a personal connection with the Pacific ... I feel it is my purpose to preserve my Pacific heritage."

The Melbourne protests come after climate change activists staged operations at three coal ports in New South Wales.

NSW Police said three people who locked themselves onto a coal-loading conveyor belt at the Port of Newcastle were arrested, while activists said two others who scaled coal-loading equipment at Port Kembla near Wollongong, were also taken into custody.