Part of Stonehenge has been covered in orange powder paint by protesters.

Two Just Stop Oil campaigners sprayed the paint on the historic site near Salisbury, Wiltshire, at around 12:00 BST on Wednesday.

The move comes the day before celebrations begin for the Summer Solstice at the 5,000-year-old landmark.

Wiltshire Police confirmed two people had been arrested on suspicion of damaging the ancient monument.

Prime Minister Rishi Sunak condemned the incident as a “disgraceful act of vandalism”.

Just Stop Oil named the two protesters as Niamh Lynch, a 21-year-old student from Oxford, and Rajan Naidu, a 73-year-old from Birmingham, in a statement.

The group said the orange powder was cornflour and it would “wash away with rain”.

Members of the public were heard shouting “no” and seen running to intervene as the campaigners ran up to the stone circle at the Unesco world heritage site.

A spokeswoman for English Heritage described the spraying of the monument as “extremely upsetting” and confirmed the site remained open to the public.

She added that curators were “investigating the extent of the damage”.

Just Stop Oil said the motivation behind the incident was to demand the next UK government end the extraction and burning of oil, gas and coal by 2030.

A spokesperson for the group said: “Continuing to burn coal, oil and gas will result in the death of millions. We have to come together to defend humanity or we risk everything.”

A spokesman for Wiltshire Police said: “We responded to a report that orange paint had been sprayed on some of the stones by two suspects.

“Our enquiries are ongoing and we are working closely with English Heritage.”