Almost a third of British people now believe the myth that there are “no-go zones” where non-Muslims cannot enter, according to a report warning of mounting intolerance.

Research by Hope Not Hate found that economic inequality was driving hostility towards Muslims, immigration and multiculturalism, particularly in post-industrial and coastal towns.

“These areas also voted strongly for Leave in the referendum and, ironically, may well suffer most under a hard Brexit – making them a ripe target for the far and populist right,” the group said.

“In effect, two Britains have emerged, with a more confident, diverse, liberal population now concentrated in our cities. The implications of this for Brexit, for the Labour Party, for politics in general, and potentially aiding the rise of a far-right movement, could all be profound.”

The research comes following an increase street protests by far-right groups including the anti-Islam Democratic Football Lads Alliance and supporters of English Defence League founder Tommy Robinson.

A 2018 YouGov survey of more than 10,300 people showed that attitudes towards Muslims had been hardening in Britain in the wake of Isis-inspired terror attacks and grooming scandals where the majority of suspects have been of Pakistani heritage.

It found that the perception of Islam as a threat was moving into the mainstream, with 32 per cent of respondents believing that there are “no-go areas in Britain where sharia law dominates and non-Muslims cannot enter”.

The view was shared by almost half of people who voted Leave in the EU referendum, and 47 per cent of Conservative voters.

Security Minister Ben Wallace: Far-right is adopting same grooming methods used by Islamists

The "no-go zones" theory, which is spread by global far-right pundits online has been widely debunked and where there have been isolated incidents of "Muslim patrols", suspects have been arrested and condemned by local Muslim leaders.

The most infamous group, called the Sharia Project, was headed by Siddhartha Dhar, an acolyte of Anjem Choudary who later joined Isis in Syria.

In the YouGov poll, a small majority felt that there was an increasing amount of tension between the different political and demographic groups in the UK.

Almost a third thought Islamist terrorists “reflected a widespread hostility to Britain from among the Muslim community”, including two thirds of Leave voters.

Hope Not Hate’s research mapped data from the YouGov poll across parliamentary constituencies to create a heat map of different attitudes.

Overall it showed that liberal attitudes are most concentrated in areas like major cities where diversity is a normal part of everyday life, and the population tends to be better educated, younger and enjoying greater opportunities.

Meanwhile, the greatest concern about immigration and Islam was found particularly in post-industrial towns and coastal areas, where populations are less diverse.

Free Tommy Robinson supporters and Pro-Trump supporters come together on Whitehall, London (PA) (PA Wire/PA Images)

Researchers documented a “halo effect” where cities with large Muslim populations are surrounded by predominantly white British areas with more hostile views.

“Where non-Muslims live, work and socialise with Muslims, these interactions are likely to reduce prejudice,” the report said. “But if people witness rather than experience super diversity, existing prejudices can be reinforced.”

Nick Lowles, chief executive of Hope Not Hate, warned of a growing cultural divide between increasingly educated, diverse and multicultural metropolitan populations and those living in smaller towns.

“Communities with the greatest anxiety to immigration and multiculturalism are also the ones which has lost most through industrial decline,” Mr Lowles said.

“These communities had failed to see any benefit in globalisation and were, if anything, going backwards … the Brexit vote was, in the eyes of many, those in the left behind communities getting their revenge.

“Views are hardening and the target of their anger is increasingly Muslims, Islam and the political establishment.”

He said a sense of loss of hope and abandonment by the government was translating into hostility towards the political system.

“Political parties will not reduce anxiety or even hostility to immigration and multiculturalism by cracking down on immigration alone,” Mr Lowles added.

“It is about rebuilding these communities, equipping their young people with the skills that will enable them to compete more effectively in the modern global world and – fundamentally – giving them a sense of hope in the future.

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“It means genuinely empathising with them, ensuring that people like them are at the heart of the party and in decision making and it is about showing through action that they care.

“All this will require money and political will, but if we are to genuinely reduce anxiety about immigration and now growing hostility to British Muslims and Islam more generally, which could have seriously bad consequences, then we have to address the underlying issues which give rise of these attitudes.”

Attitudes were found to be heavily influenced by age, social deprivation and education.

All 100 areas where people were found to be the most hostile towards immigration and multiculturalism were in towns or on the outskirts of cities, with 93 in the Midlands or north of England.

But the 100 areas most associated with “confident multicultural” populations were in central city areas and close to universities.

Younger people were less likely to be concerned with immigration, oppose diversity or believe that Muslims were “hostile to Britain” than over-65s.

Three quarters of people with university degrees thought that having a wide variety of backgrounds and cultures is part of British culture, and that immigration has been good for the country, compared to just 45 per cent of people educated to GCSE level.

Rosie Carter, who led a public engagement exercise for the research, said: “To fight fascism, we understand the need to take the economic link seriously.