RUSSIAN interference in the EU referendum must be investigated by UK security services in the same way that the US intelligence chiefs are probing similar “meddling” in the US presidential election, the SNP has said.

A senior MP involved in a high-level committee investigation into Russian-backed social media accounts - accused of attempting to influence public opinion before the UK narrowly voted to leave the EU - claimed the Kremlin tried to “undermine our democracy” and said Prime Minister Theresa May must order a probe.

Brendan O’Hara, who sits on the influential House of Commons Digital, Culture, Media and Sport Committee, warned against “complacency” as their inquiry into tech giants Twitter and Facebook’s role in the dissemination of “fake news” is stepped up.

He said: “Theresa May was absolutely unequivocal in her speech last week about interference by Russian-backed accounts during the EU referendum campaign. If she has evidence that Russian sites did influence the referendum, it must be investigated because we’re talking about the undermining of our democracy here.”

Facebook and Twitter have come under increasing scrutiny after it emerged hundreds of Russian-backed accounts reached as many as 126 million Americans during the 2016 presidential election.

Lawyers representing Facebook and Twitter were grilled by members of the US Senate Intelligence Committee last week about the role their platforms played in Russian attempts to influence voters.

READ MORE: Suspended Russian Twitter accounts also mentioned Scottish independence debate

Damian Collins MP, chairman of the House of Commons’ Digital, Culture Media and Sport Committee, has written to Facebook CEO Mark Zuckerberg and the chief executive of Twitter Jack Dorsey to ask for information which could “link fake news, bot accounts and fake accounts to Russian-backed activity in the UK around the Brexit referendum and around our election, too.”

“I think we have a right to know what was going on here,” he said. “Some evidence has already emerged that known Russian accounts were active in UK politics around that time, that’s as a consequence of evidence that’s been discovered in America. But I want to see what was going on here and I think those companies owe it to us to produce that information for a parliamentary committee that’s requested it.”

Last month a federal grand jury indicted Paul Manafort, Trump’s former campaign chairman, and his business associate Rick Gates, on charges that included conspiring against the US and money laundering. In addition, George Papadopoulos, a former foreign policy adviser to Trump’s campaign, pleaded guilty to perjury over his contacts with Russians linked to the Kremlin.

The US intelligence community has concluded that Russia tried to sway the presidential election but Donald Trump has said Vladimir Putin told him he “absolutely did not meddle in our election” when the pair met at last week’s Asia-Pacific summit.

Thousands of social media accounts were recently released to the US Senate Intelligence Committee investigating Russian interference in the presidential election and it has emerged some were also active in the UK during the EU referendum campaign.

Damian Collins warned: “I think there’s a strategy they [the Russians] are deploying in different countries – in America, in France, and we’re starting to see it in the UK as well. This is a tool and a weapon they’re using to destabilise other countries.”

Collins said there has been a push to “micro-target” users and “bombard them with fake news and hyper-partisan messaging so that the news they see and consume through these social media sites is massively biased or, indeed, some of it fake.”

Theresa May said last week Russia has “mounted a sustained campaign of cyber espionage and disruption”.

She said this included meddling in elections, and hacking the Danish Ministry of Defence and the Bundestag.

May said Russia is seeking to “weaponise” information by “deploying its state-run media organisations to plant fake stories and photo-shopped images in an attempt to sow discord in the West and undermine our institutions.”

Collins said social media companies must be challenged and users educated, but SNP MP Brendan O’Hara said the UK government must do more to probe Russia’s involvement.

“We need to know how deep this went,” O’Hara said. “The fact that it happened, and has been acknowledged as happening, deserves further investigation.”

Before he was elected O’Hara was a journalist and television producer who worked for STV, the BBC and Sky. He said the UK has been “caught off guard by fake news”.

“I don’t think people really understand how dangerous and pernicious it is,” O’Hara said. “There’s also a sneering that some daft Americans might fall for it but we wouldn’t. We absolutely would. So, I think there is a complacency about our ability to spot fake news.

“We as a country are playing catch up and I think the committee investigation and subsequent report will play an important part in highlighting how dangerous fake news is. If it’s not challenged or highlighted the lines between what’s real and what’s fake, which are already blurred, will become more unclear.

“I’d like to think that the UK security services are taking this very seriously and are doing some work on it. Whether it’s Russia, or any other country, it’s being done to undermine or destabilise our democracy.”

Phillips Payson O'Brien, a professor of strategic studies at the University of St Andrews school of international relations, also suggested there should be a wider investigation in the UK.

He said: “We know there are Twitter and Facebook accounts that are pumping out information that represents what the Russian government sees as Russia’s interest and Russia certainly doesn’t like a united Europe. Brexit is in Russia’s interest. What we don’t know is how deep it is. It would be good to know more before we can say there was a huge concerted effort in the UK.”

A spokesman for the Prime Minister declined to comment.