Ethnic minorities in Britain are facing rising and increasingly overt racism, with levels of discrimination and abuse continuing to grow in the wake of the Brexit referendum, nationwide research reveals.

Seventy-one percent of people from ethnic minorities now report having faced racial discrimination, compared with 58% in January 2016, before the EU vote, according to polling data seen by the Guardian.

The data comes amid rising concern at the use of divisive rhetoric in public before this week’s European parliament elections, where some leading candidates, including Ukip’s Carl Benjamin and the independent Tommy Robinson, have records of overt racism.

The survey by Opinium suggests racists are feeling increasingly confident in deploying overt abuse or discrimination. The proportion of people from an ethnic minority who said they had been targeted by a stranger rose from 64% in January 2016 to 76% in February this year, when the most recent polling was carried out of 1,006 people weighted to be nationally representative.

The trend appears in line with crime figures, which have shown that racially motivated hate crime has increased every year since 2013, doubling to 71,251 incidents in England and Wales in 2018, according to the Home Office.

David Lammy, the Labour MP for Tottenham and a leading anti-racism campaigner, described the findings as “alarming”, while Omar Khan, the chief executive of the Runnymede Trust, a race equality thinktank, said it was now clear that Brexit, while not the source of racism, had led to higher levels of racism being expressed and that social media was “normalising hate and increasing division”.

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The poll comes amid a wave of headlines about racism in Britain, from the BBC’s sacking of Danny Baker for tweeting a picture of a couple with a chimp following the birth of the Duke and Duchess of Sussex’s baby, to growing anger from professional footballers at racism online and in stadiums.

Meanwhile, the Conservatives and Labour have been tainted by allegations of Islamophobia and antisemitism respectively.

The survey found that at the end of 2016, 37% of people saw racism on social media on a day-to-day basis, but that has now risen to 50%, and is even higher for younger minority ethnic people aged 18 to 34.

Online racism has more than doubled since before the referendum, to 51%, and there were rises of about 50% in the number or people reporting hearing people ranting or making negative comments about immigration or making racist comments made to sound like jokes.

People from a black background reported the greatest increase in discrimination, with the proportion saying they had been abused or discriminated against rising from 59% in January 2016 to 65% the following October and to 74% this February and March, when the latest poll was conducted. Respondents from the east of England were most likely to say they had suffered racism.

Minority ethnic women also reported a sizeable increase, with 74% saying they had faced racial discrimination this year, compared with 61% in the latter half of 2016. This increase in racial discrimination is mainly down to racism from strangers. Looking at the types of racial discrimination faced, the proportion saying they have experienced someone making a racist comment in jest has risen to over half (55%) of people from ethnic minorities.

Lammy said: “It is no coincidence that this rise has come as anti-migrant populists seek to divide the country using the playbook of Donald Trump.

“This has both legitimated and encouraged abuse online and in the real world. I have experienced first-hand the rise in racist content on social media, and the level of abuse experienced by the younger generation makes dealing with this problem of paramount importance.”

Khan said: “The EU referendum has both revealed and amplified the experience of racism among ethnic minorities in Britain.

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“Even before the referendum a clear majority of Britain’s 8 million ethnic minorities reported experiencing racism and being targeted with overt discrimination. Following the referendum, these figures have now risen to around three in four ethnic minorities, meaning that millions of ethnic minorities have been targeted with overt racism.”

He said the large rise in racism on social media raised concerns about whether online channels were normalising hate and increasing division.

“Rather than dismissing or ignoring the extent of racism, it’s important for politicians – as well as media and social media companies – to show leadership in challenging racism,” he said. “Britain’s leaders must reflect on how they can ensure Britain’s ethnic minorities feel safe and secure, and have equal opportunities and choices in where they work, commute and live.”

There were small falls in the number of people who felt they were victims of more tacit forms of discrimination such as being treated with suspicion by police or security guards, being turned down for promotion at work or suffering workplace bullying.