Animal Rebellion protesters have poured milk on to the floor in shops across the country.
The group co-ordinated the action in stores including Waitrose, Whole Foods and Marks and Spencer in London, Norwich and Edinburgh just before 12pm on Saturday.
Footage online shows several protesters pouring milk from the shelves in the Norwich Marks and Spencer in front of horrified shoppers.
Norwich Police confirmed four people had been arrested following the incident for offences of assault and criminal damage.
Elsewhere, one group poured milk out in Harrods' food hall in Knightsbridge.
Another was filmed emptying milk bottles on to the floor and across a table laden with cheeses in Fortnum and Mason in Piccadilly.
Animal Rebellion said it is calling for a plant-based future and highlighting the need to support farmers in transitioning to a sustainable plant-based food system.
Lou Hadden, a charity worker from Herefordshire who joined the action at Fortnum and Mason, said: "This is not how I imagined spending my weekend.
"Unfortunately, this disruption is necessary to get those in power to listen to the academics at Oxford, Harvard and the IPCC (Intergovernmental Panel on Climate Change).
"The world's best climate and land scientists are calling for the transition to a plant-based food system.
"We need bold and decisive politics at this time, not the horror show we currently see."
Meanwhile, Skylar Sharples, an international development graduate from Bristol and one of the protesters at Harrods, said: "Supporters of Animal Rebellion are back acting because [Prime Minister] Liz Truss and Ranil Jayawardena [Secretary of State for Environment, Food and Rural Affairs] are again deciding to ignore calls to start building a better future.
"A plant-based future would see a beautiful world for us all, thriving with nature and life."
One person reacted to the Animal Rebellion tweet saying it was a protest which was impossible to defend.