Two environmental activists put pies on the wax figure of King Charles III.
thrown at London's Madame Tussauds.
After the protest on Monday morning, the two and two other people were arrested for damage to property, the police said.
Several videos released by protest group Just Stop Oil show a man and woman standing next to the figures of the royal family, unveiling their T-shirts with the organization's name on them, and finally throwing a cake at the face of the wax figure.
The British government should completely stop issuing new permits for oil and gas production, it said in a statement on social media.
The monarch allegedly recently decided, on the advice of Prime Minister Liz Truss, not to attend the world climate summit and not to give a speech there.
The COP27 is scheduled to take place in Egypt in November.
As the British head of state, the king has traditionally had to act in agreement with the government.
Last week, however, Truss announced her resignation.
About a week and a half ago, activists from the same protest group threw tomato soup at the famous painting "Sunflowers" by Dutch artist Vincent van Gogh in the National Gallery in London.
The work was protected by a pane of glass, the frame was slightly damaged.
On Sunday, two climate activists from another group carried out a similar attack on a valuable painting by the French impressionist Claude Monet in Potsdam's Barberini Museum.