Environmental protesters have sparked outrage after spraying England’s prehistoric Stonehenge monument with orange paint.

Footage shows two Just Stop Oil activists, armed with spray canisters, running towards the megalithic rock structure.

They are seen spraying paint onto the Stonehenge blocks as another person attempts to stop them.

The attack on one of the UK’s most visited tourist sites came on the eve of the summer solstice celebrations.

The group said it used orange cornflour paint to spray onto the stones, which it claimed would “soon wash away with the rain”.

Two people were later arrested on suspicion of damaging the ancient monument, police said in a statement.

The public used to be able to walk around within the stone circle. It was fenced off in 1977 due to concerns about damage from a sharp rise in visitor numbers.

Located in southern England, Stonehenge is a UNESCO World Heritage Site.

British Prime Minister Rishi Sunak said the protest group was a “disgrace”.

Labour leader Keir Starmer said:  “The damage done to Stonehenge is outrageous.

“Just Stop Oil are pathetic.”

English Heritage, the charity that manages Stonehenge, said on X that the site remained open.

“This is extremely upsetting and our curators are investigating the extent of the damage,” it said.

Just Stop Oil has gained prominence in Britain for disruptive environmental protests, with its activists shutting down major roads, disrupting cultural and sporting events and even throwing soup at a Van Gogh painting.

The group wants the British government to end the extraction and burning of oil, gas and coal by 2030.

The incident happened on Wednesday at about midday (local time), the day before the summer solstice is celebrated at Stonehenge, which is at the heart of a World Heritage site.

About 8000 people gathered at Stonehenge to mark the longest day of the year in 2023. Similar numbers are expected on Thursday.