NSW Police has a message for climate activists who caused chaos for Monday morning commuters in Sydney – expect a knock on your door.

Protesters took to the streets of the CBD in an unauthorised demonstration to protest political inaction on climate change.

Terrifying aerial vision has captured the moment one vehicle ignored traffic controllers, driving into police and protesters blocking traffic.

Strike Force Guard detectives are aware of the vision and are conducting inquiries.

It is not known if anyone was injured during the incident.

Demonstrations began around 8am at Hyde Park, where police allege about 60 protesters joined protest activity across the city’s streets.

Eleven people have been arrested, the majority taken to Surry Hills and Day Street police stations, where charges are expected.

Protesters threw concrete blocks, garbage bins, bikes and ladders onto the city streets in an effort to disrupt traffic and delay police officers trying to put a stop to the protest.

“The behaviour of this group was nothing short of criminal activity,” Acting Assistant Commissioner Paul Dunstan told reporters on Monday afternoon.

He described the protesters’ behaviour as “incredibly dangerous, unacceptable” and “violent”.

There have been no reports of injuries at this stage.

NSW Police trailed the parade of protesters on foot and via a convoy of vehicles with sirens wailing, cleaning up after the protesters in an attempt to clear roads.

The Sydney Harbour Tunnel has reopened after a protester parked a car across the road at the southbound entrance around 8am.

Blockade Australia has identified the protester as 22-year-old Mali, who live streamed themself disrupting traffic at the tunnel with her head locked to her steering wheel with a bike lock.

A man can be heard approaching the car and angrily shouting profanities at the protester.

“To those people who are really angry right now, I understand, and it’s not a good thing to be experiencing. You know what? Climate change isn’t a good thing to be experiencing,” Mali said.

The 22-year-old Lismore resident was arrested and taken to North Sydney police station, where charges are anticipated.

Police have since removed the vehicle and all lanes of traffic have reopened.

“It’s been a pretty full-on year,” Mali said on the live stream.

“I was lucky but I was in Lismore for both of the major floods.

“I’ve seen a lot of devastation, I’ve seen people that I love lose everything, I’ve seen places that I love be destroyed.”

NSW Premier Dominic Perrottet has weighed in on the protest action by writing into 2GB radio station.

“These people are bloody idiots, and they will face the full force of the law,” Mr Perrottet said.

Police have confirmed that protesters will be charged under new protest laws passed in April.

Protesters can be fined up to $22,000 and/or jailed for a maximum of two years for protesting illegally on public roads, rail lines, tunnels, bridges and industrial estates.

Police will continue to review CCTV and other video sources to identify and arrest those involved in the protest.

“There is a way to do it and way they did it today is totally unacceptable and will not be tolerated,” Assistant Commissioner Dunstan said.

“Expect a knock on your door. We will be coming to arrest you.”

The protest action comes a week after police raided a camp in Colo Valley, north of Sydney, where about 40 climate activists were found preparing for the week-long disruption.

The climate action group has been vocal about the protests since March when they conducted a series of extreme stunts across the CBD to disrupt commuter traffic.

Police will continue to patrol major roads and highways leading into the CBD as well as previous protest locations, including Port Botany and railway stations, throughout the week.

Blockade Australia will hold a press conference at 2.30pm at Redfern Park.

- by Madeleine Achenza, news.com.au