There were gasps, roars and a shout of “Oh my gosh!” in room 43 of the gallery as two young supporters of the climate protest group threw the liquid over the painting, which is protected by glass, just after 11am.

They removed jackets to reveal Just Stop Oil T-shirts before gluing themselves to the wall beneath the artwork, which is one of the gallery’s most important treasures.

“What is worth more, art or life?” said one of the activists, Phoebe Plummer, 21, from London. She was accompanied by 20-year-old Anna Holland, from Newcastle. “Is it worth more than food? More than justice? Are you more concerned about the protection of a painting or the protection of our planet and people?

“The cost of living crisis is part of the cost of oil crisis, fuel is unaffordable to millions of cold, hungry families. They can’t even afford to heat a tin of soup.”

National Gallery staff quickly cleared the room. The gallery has since confirmed the painting was not harmed, saying in a statement that after the protesters threw “what appears to be tomato soup” over the painting, “the room was cleared of visitors and police were called. Officers are now on the scene. There is some minor damage to the frame but the painting is unharmed.”

The activists were subsequently arrested by Met police officers for criminal damage and aggravated trespass and taken into custody at a central London police station.

The canvas of the painting is protected with a glass screen, a factor Just Stop Oil said they had taken into account.

The picture is one of the most famous images in the world, painted by the Van Gogh when he lived in the south of France. The image, like so much of the Dutch artist’s work, celebrates the beauty of ordinary everyday objects – a flower, a chair, a shoe. In 1987, one of the series was sold for $39m.