Smoke flares were also set off alongside the Grade I-listed monument, which is nearly 200 years old.

Campaigners used fire extinguishers to spray the paint as part of the protest against new fossil fuel licences.

According to the Just Stop Oil website, one of those taking action at the monument was Joshua Lane, 26, an engineer from Sheffield, who said: "I am compelled to take action due to the severity, and sheer emergency we find ourselves in today.

"Future generations live in uncertainty, and we are given false promises time after time by endless pantomime governments."

Another of the activists, Joe Hogan, 40, from Hertfordshire, said: "Traditional, managed, sanitised forms of protest have done nothing.

"The only way forward is through sustained, disruptive civil resistance."

The protest comes just weeks after the government backed the development of the UK's largest untapped oil and gas field at Rosebank, 80 miles west of Shetland.

It came despite warnings about the climate damage of new fossil fuel projects and with analysis showing the project is likely to have little positive impact on the British economy.

The Met Police confirmed it was made aware of the protest just before 10.20am on Wednesday and three people were arrested on suspicion of criminal damage.

The protest comes after three other climate campaigners were each given a 12-month community order and 60 hours of unpaid work for invading the pitch at Lord's cricket ground in London.

Read more:
'Rosebank helps label Tories as party of the past'
Oil field approval is 'abject madness', says Packham
Who are Just Stop Oil?

Judit Murray, 69, Daniel Knorr, 21, and Jacob Bourne, 27, were sentenced at Westminster Magistrates' Court on Tuesday for stopping play during the second Test between England and Australia on 28 June.

In a separate case at the High Court, 12 Just Stop Oil supporters are accused of breaching a court injunction by staging a protest on the M25 in November last year.

On Tuesday, 76-year-old grandmother Gaie Delap, from Bristol, told the judge in the hearing she had climbed on to a motorway gantry because the "climate emergency" was not being taken seriously enough.

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