Published: 4:14 PM November 8, 2018 Updated: 6:26 PM September 17, 2020

Mysterious billboards celebrating the UK and Russia's 'Brexit collaboration' have been erected across London.

A billboard featuring Russian leader Vladamir Putin, in Stoke Newington, north London Photo: PA / Caitlin Doherty - Credit: PA Wire/PA Images

A group calling itself Proud Bear, which claims to be a 'collective of Russian intelligence agents' are behind the billboards.

One reads 'Let's celebrate a red, white and blue Brexit' accompanied by a picture of a winking Vladimir Putin waving a Russian flag.

Another proclaims 'Thank you! Boris', picturing the former foreign secretary and leader of the Vote Leave campaign group Boris Johnson waving Russian flags.

READ: Pain game: UK set to lag behind Europe after Brexit

But evidence points to a band of British volunteers and satirists who are calling for an official investigation into Russia's influence on the EU Referendum being behind the posters.

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The Proud Bear posters, and Twitter account associated with the campaign, encourage viewers to visit a website where the group hopes to raise £55,000 for an advert on the 40-metre-wide LED screen at London Waterloo train station.

One man, who took photographs of the billboard in Stoke Newington, said he thought they were 'hilarious'.

'Given that the whole world is falling apart, it doesn't seem too far-fetched that Russian interference could have had something to do with it,' he said.

'Stuff like this is good. People need to see more of it and call people out,' he added.

Tens of thousands of Twitter accounts are understood to have tweeted pro-Brexit messages in the build up to the EU Referendum in 2016, but the impact of the messages has not been accurately assessed.

But hidden in the website's source code is a message, written in Russian, which reveals the true sentiment behind the posters.

'Theresa May prefers to promote Brexit's ridiculous plan instead of stopping for a moment and truly investigating the question of whether Russia's influence was really decisive in the vote.

'The UK immediately needs a Muller-style investigation into Russian intervention in the Brexit campaign,' reads part of the script when translated into English.

The Cabinet Office and Mr Johnson both declined to comment.

Organisers said the 'hostile message' in the website source code is 'CIA website hacking', responding to a request for comment.

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