“Malicious actors” including hostile states and far-right extremists will use Britain’s exit from the European Union as an opportunity to sow division and disinformation, MPs have been warned.

The Home Affairs Committee heard that automated bots, real-life extremists and state-sponsored “troll farms” could use Brexit on 29 March to undermine the values of British democracy.

Experts said that Russia-affiliated accounts had also been posting “hateful” anti-Muslim messages and amplifying real-world far-right activity.

Chloe Colliver, a project manager at the Institute for Strategic Dialogue thinktank, said: “The fall-out of Brexit will be a point of vulnerability in which malicious actors, either state or non-state, will have an opportunity to try to sow discord, division and disinformation.”

Police and the military are bracing for possible protests and disorder around Brexit, with some groups threatening riots if the UK does not leave the EU under the terms they want.

Russia has been named as the main culprit behind misinformation campaigns during the US presidential election and others in countries including Germany and Sweden, while Iran and Saudi Arabia have also been behind recent activity.

Speaking at an evidence session on Tuesday, experts said state actors were using existing grievances and political events in the UK to sow “chaos” and undermine faith in the democratic process.

Alex Krasodomski-Jones, a social media analyst at Demos, said that although far-right messaging was found to be amplified by Russian actors, influence operations are “playing both sides”.

He told the committee: “The point is chaos, the point is not knowing what is true and what is not true, and anger above all else.”

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Mr Krasodomski-Jones said Russian-linked accounts had already used Brexit and terror attacks to sow discord.

He said content spread after last year’s attacks in London and Manchester was “hateful”, and replied the affirmative when committee chair Yvette Cooper asked whether the activity amounted to “Russia-sponsored promotion of Islamophobia in the UK”.

Jacob Davey, research manager at the Institute for Strategic Dialogue, described Russia as a “chaos agent”.

“They will throw everything at the wall to see what sticks and it isn’t just the far right being targeted,” he added.

The Home Affairs Committee is investigating potential links between far-right extremism online and potential real-world violence, following the Finsbury Park terror attack.

Police said the perpetrator, Darren Osborne, was radicalised in a matter of weeks as he consumed a huge amount of social media posts by anti-Muslim figures including Tommy Robinson and Britain First.

Four far-right terror plots have been foiled since the Westminster attack in March last year and white terror suspects have become the single largest ethnic group arrested.

Assistant commissioner Neil Basu recently warned that Islamist and far-right ideologies are “feeding each other” and that a rise in Islamophobic and antisemitic hate crime could be seen as a proxy for the rising terror threat.

British security services have been increasing their efforts against the extreme right-wing following the ban on neo-Nazi terrorist group National Action two years ago, and MI5 is taking an increasing role in intelligence investigations.

Britain before Brexit: East of England Show all 13 1 /13 Britain before Brexit: East of England Britain before Brexit: East of England Norwich A couple and their dog relax by the Cathedral’s Labyrinth. I am charmed by the arrangement of their bodies and the shapes in which they are bonding. I realise the contemporary significance of the scene: the labyrinth - a complicated, irregular network of passages in which it is difficult to find one’s way - alongside the simplicity and closeness of human togetherness. In any complicated maze-like structure - Brexit included - it is important to remember that people and love and relationships are a vital part of the picture. Richard Morgan/The Independent Britain before Brexit: East of England Luton A construction worker assembles metal barriers for an art event. He looks towards an off-licence boasting to be pure 100% Moldovan. The lady inside isn’t returning the gaze, but stares inwards, onto the surface of her selfie, her narcissism being by far the most interesting thing in the shop window. Richard Morgan/The Independent Britain before Brexit: East of England Luton Walking back into town from Leagrave High Street I notice two graffitied propaganda messages: ‘Free Gaza’ and ‘Beverly is a black cow’. Here are but two voices, I think, in the crazy cacophony of contemporary British discourse, of the British tongue, fractured as it is into accents, splintered by slangs, torn, in this case, into the libertarian and abusive, one dehumanising, one for freedom. Richard Morgan/The Independent Britain before Brexit: East of England Cambridge University students hold a flash protest against the low pay of McDonald’s employees. They receive tuts, cheers, insults, whoops, raised eyebrows. People enter the restaurant in any case, unaware or uncaring that they have crossed a picket line. Richard Morgan/The Independent Britain before Brexit: East of England Norwich I went to look inside the Catholic Cathedral during Mass. I wanted to see the ritual and the practices, the people and their poses. There is a rich spectrum of visual dimensions to Catholic prayer that I first noticed when photographing in Poland. I’m attracted to its ambivalence: solemn and joyous; lonely in dialogue; desperate but determined; solitary yet complete. Richard Morgan/The Independent Britain before Brexit: East of England Great Yarmouth Posters from the town’s glory days surround the Winter Gardens as it rusts and becomes overgrown. It seems like an intentional act to rekindle nostalgia in the face of disrepair, to balance the present with representations of the past. Richard Morgan/The Independent Britain before Brexit: East of England Norwich At the back of the central market hang three representations of conflict, side-by-side, connected, making sense in relation to one another. Only one message can be worn at any one time, but together they narrate a powerful image of modern Britain: a unified group, a club, an undefeated nation facing an existential threat from its enemies. Richard Morgan/The Independent Britain before Brexit: East of England Luton People set up posts outside the train station, asking the town’s new arrivals for various things: religious missionaries seek attention and commitment; a person sleeping rough asks for food and spare change. I’m interested in how this affects the visual experience of arriving in Luton and what the religious and the homeless look like when viewed in the same frame. Richard Morgan/The Independent Britain before Brexit: East of England Cambridge A concoction of interests outside King’s College: a tourist desperately hailing lost members of the group; a shopper takes a break from the high street; a man sits to read; a woman meditates with her identity concealed. Richard Morgan/The Independent Britain before Brexit: East of England Luton A family emerges from the colours of Leagrave High Street. Twins sit and stare, identically, scrutinising me, like their father, perhaps. They are framed by rails of clothes. Mannequins exaggerate their life. Richard Morgan/The Independent Britain before Brexit: East of England Luton A pop-up employment workshop opens for business in the town centre. The sign is heavily loaded with the values of modern Britain: one must aspire to achieve, earn, and live; acquiring skills is akin to personal development; the prioritisation of the ‘local’. A lady carrying water on a scooter - unconventionally, comically, skilfully - appears as a strange detail of everyday life passing such lofty visions. Richard Morgan/The Independent Britain before Brexit: East of England Great Yarmouth The Britannia Monument celebrates Horatio Nelson’s life. An acrobat fell from the top and died in 1863. It remains a mystery, a travesty for some, that Britannia - the monument’s embodiment of the nation - has her back to the sea. These days she turns her back on a single one-man tent too, a home, a shelter erected on the shore. Richard Morgan/The Independent Britain before Brexit: East of England Great Yarmouth This was the last scene I saw in the town. I was leaving. I thought of how child’s play, in its innocence and vitality, continues amidst our hunched, phone-tapping adolescence and adulthood. Richard Morgan/The Independent

Experts told MPs that while social media companies have vastly improved the detection and removal of Isis propaganda and other Islamist content, efforts against the far-right are lagging behind.

Stephen Doughty, the Labour MP for Cardiff South and Penarth, said evidence previously given to the committee by Twitter, Facebook and YouTube showed that they were “grossly underestimating this threat and not putting enough resources in”.

Mr Davey said extremists around the world were increasingly amplifying each other’s messages and talking points.

He cited the “Free Tommy” Robinson campaign as an example and said 47 per cent of analysed tweets discussing the anti-Islam activist’s imprisonment were sent from the US.

“What this represents is the building of an international consensus around far-right activists and common tactical playbooks,” Mr Davey said. “If you pick particular examples it’s on a very large scale.”

He said that social media activism had lowered the “barrier to entry” into far-right movements and personal risk for people who might be alienated by their peers for joining a street movement.

Britain First’s now banned Facebook page once had more followers than all mainstream UK political parties combined and Tommy Robinson’s page has more than one million followers.

Facebook, Twitter, Instagram and other social media giants have been mounting their crackdown on far-right figures but researchers said the removal of high-profile accounts risked pushing members of the public into unregulated networks where extremism goes unchallenged.

Experts said the increasingly fractured online landscape makes it difficult for either the government or social media companies to crack down on the proliferation of extremist content that falls below a criminal threshold.

Mr Davey said uncontroversial issues, such as ideas of free speech, are being used as “soft narratives” to take people onto a path of radicalisation

“There is an awareness of what you can say legally and within the parameters of particular social media platforms to not get kicked off,” he added.

Ms Colliver warned that extremists were seizing mainstream political discussions to reach new audiences and drawing people into a “radicalisation ecosystem” that could lead to real-world action.

Following the imprisonment of a neo-Nazi British soldier who had been recruiting for National Action, Mr Davey said the armed forces and police were a particular target for the far-right.

He warned that while alternative social media and video hosting platforms exist, takedowns of extremist accounts will have a limited impact and called for work to focus on raising awareness, online education, resilience and counter-narratives.

Experts called for the government to provide clarity to social media companies on what content should be removed, and said algorithms currently geared towards terrorist material should be reworked for wider extremism.

Ms Colliver said the loose structure of online movements made them difficult to ban.