Russian propaganda adverts backing Brexit had four times more impact on Twitter than the official Leave campaigns claim.

Kremlin-backed channels RT and Sputnik pumped out 260 anti EU stories which were shared so widely on Twitter they were seen up to 134 million times online.

This dwarfs the number of posts from the Vote Leave and Leave.eu campaigns, which were seen up to 33 million and 11 million each respectively.

Researchers said the findings show that the Kremlin 'won the Twitter war' and tried to interfere in Britain's politics.

The research, put together by 89up - a communication and social media analytics company - was submitted the report to MPs investigating the role of fake news.

It comes after Twitter bosses admitted last week that a single Russian troll factory ran 49 accounts and pumped out nearly 1,000 messages to try to sway the referendum.

Moscow-backed channels RT and Sputnik pumped out 260 anti EU stories which were shared so widely on Twitter they were seen up to 134 million times online (file pic of the Kremlin)

Mike Harris, its chief executive, said: 'It is a scandal that a foreign power has attempted to interfere in British democracy.

'Parliament must investigate how much the Russian government is paying social networks for their propaganda and Facebook and Twitter need to get a grip on the use of their networks by regimes who hate democracy and our values.

What are the claims concerning Russian interference in the EU referendum and why are MPs investigating them? Moscow has been accused of trying to interfere in the Brexit referendum by posting fake news and propaganda online. Russian bots and Kremlin-backed propaganda channels like Sputnik and RT are accused of posting Leave- backing articles in a bid to sway the vote. The allegations come amid evidence that the Kremlin tried to interfere in presidential elections in the US, France and elsewhere. Experts believe Moscow is turning to fake news and cyber propaganda to try to weaken Western democracies and multilateral cooperation. British MPs on the culture and media select committee have launched an investigation into fake new to probe the claims. And they made history by travelling to the US last week to take evidence from the chiefs of social media companies including Twitter after blasting the meagre written responses they got to their enquiries. Theresa May has publicly rebuked Russia for pedaling fake news in a bid to interfere with Western democracies. And she is launching a fake news unit to take on the growing threat. Advertisement

'During the EU referendum, we found that the reach of Russian propaganda on Twitter was greater than that of both official Leave campaigns combined.

'Regardless of your views on Brexit, it's important we know if public opinion is being manipulated by foreign states.'

Researchers came up with the figure by adding the number of times the post on Twitter was scrolled on and therefore could have been seen.

The agency 89up has worked for Best for Britain, a campaign to keep the UK in the European Union, but said it funded this piece of research itself.

The report details the sheer scale of Moscow's attempts to interfere in the historic EU referendum, and it warns: 'Russian state media propaganda through Facebook and Twitter led to significant online traction'.

It said that the Russian propaganda was 'starkly' pro Leave and that their articles were 'shared more than content from both of he actual Leave campaigns.'

It adds: 'Russian state media articles won the Twitter war - with significantly more Twitter impressions than any content from either anti-EU campaign website.'

It would have cost Leave campaigners around £1.35million to buy the kind of coverage which RT and Sputnik peddled out for them for free, researchers said.

The report said that social media companies like Facebook and Twitter face a number of serious questions following their research.

This includes how much RT and Sputnik actually spent n their platforms in the lead up to the vote, and will they check if articles are actually being pumped out by Russian bots.

The research was handed to the culture and media select committee of MPs who are investigating fake news.

It comes amid claims that social media sites were hijacked by Kremlin-backed propaganda channels and bots which pumped out articles to try to sway the referendum vote.

Twitter - including its chairman Jack Dorsey, pictured - must do more to spell out exactly what they are doing to try to crack down on Kremlin interference in British politics, the report by 89up found

Damian Collins, the committee chairman, said that social media companies such as Twitter and Facebook should notify Britons who may have been exposed to propaganda during the campaign.

His committee last week heard evidence from Twitter executive Nick Pickles who said a single troll factory sent out some 942 messages during the fiercely contested referendum vote.

But he insisted the suspect accounts won 'very low levels of engagement' from users.

The culture committee is investigation fake news amid fears the Brexit vote could have been influence by interference from abroad.

Similar investigations are being carried out by US politicians into Donald Trump's election as President.