Just Stop Oil protesters have sprayed paint over a luxury car showroom and blocked Park Lane in central London.
The campaigners, who are calling for the Government to halt all new oil and gas licences and consents, set up the roadblock from 11am on Sunday.
Demonstrators sat down in the road, holding large orange banners, with a number gluing themselves to the tarmac or locking themselves together.
One protester then sprayed orange paint over the nearby Aston Martin showroom in Park Lane.
Photos and footage from the scene showed police officers trying to talk to those blocking the road while a cordon was set put up around the activists.
Chloe Thomas, 19, a pregnant mother and freelancer from Cannock who joined the action, said: “How do I explain to my daughter in the years to come where the animals went, where the culture went, where the beauty went, why there are no bees and why I can’t put food in her tummy?
“You know it’s bad, don’t you? As citizens, as humans, as parents and children we have a responsibility and a right under British law to protect ourselves and those we love.”
Patrick Michael John McCarthy, 67, a carer from Telford, who was also at the protest, said: “Please understand these actions are not easy for any of us.
“It is uncomfortable, sometimes frightening and financially draining, so why do it?
“Because we have seen the devastating truth about the existential threats we face and cannot ‘unsee’ that. The real question is why millions aren’t in civil resistance rather than why I am.”
The action comes just days after Just Stop Oil protesters threw tins of tomato soup over Vincent van Gogh’s Sunflowers painting in the National Gallery and sprayed paint over the rotating New Scotland Yard sign.
The campaign group said it will also be protesting outside Downing Street every day in October.