Mr Brown said the polling showed political parties needed to dial down the rhetoric in the election campaign and produce manifestos which could unite the UK rather than cause further division.

Speaking last night at a Hope Not Hate summit in London, he said there was “a real risk” the general election campaign could further undermine the cohesion of the UK as new polling showed that 44 per cent of Remain voters and 51 per cent of Leave voters believe politicians to be “habitual liars”.

The poll, which was carried out by the anti-racism organisation, also showed that 93 per cent of Britain’s black and minority ethnic community believe racism is on the rise, 56 per cent have experienced harassment, while 70 per cent of 18-24 year olds report racial intimidation on social media.

Former prime minister Gordon Brown warned that Brexit could lead to years of disunity and called on political parties to dial down the rhetoric in the election campaign. Picture: PA

Mr Brown said: “It will take far more than an election – perhaps a generation – to end our country’s now-widening divisions and to drain the poison that is increasingly infecting our national life.

“A huge majority of people in Britain – 77 per cent – now think that Brexit is fuelling prejudice and is making our country more divided than ever.

“With more parliamentary candidates than ever sacked because of racism, sexism or homophobia, more and more social media activists exploiting the internet to troll and abuse and with fake news debasing our public discourse, and with – it is sad to say – so many women giving up as MPs in the face of threats of violence, our country’s bitter divisions are now not just over Brexit but between north and south, rich and poor and between the four nations that, until recently, formed a cohesive United Kingdom.”

The former Labour leader, who has been increasingly active in politics since he retired from the House of Commons in 2015, accused the Conservatives of “whipping up” English nationalism, and said “rebuilding national unity” needed to be a priority for Labour, if it became the new government.

He said: “With the SNP now threatening the hardest of ‘hard’ separations and the Conservatives whipping up English nationalism with their claim Scotland will run England if there was a Labour government, nationalists on both sides are more interested in exploiting divisions rather than ending them.”

But he said it was “not too late for serious parties to rise to the challenge of reuniting our riven and discontented country”.

“On 12 December we can resolve some of the urgent challenges – Brexit, austerity and the NHS – facing the country and for that we need a Labour government – but all of the United Kingdom will have to work far harder to heal the wounds of recent years.”

He added: “Rebuilding national unity requires – as a starting point – tackling head-on, divisive nationalisms and racism – not least with new laws to root out antisemitism and Islamophobia.

“It will also require politicians to reach out to and enter into a dialogue with the public, through, for example, citizens’ assemblies and a constitutional convention, to reinvigorate our public square and revamp failing institutions. And it will need measures to end the economic insecurity that is the breeding ground for populist nationalism.”

However Mr Brown came under fire from both the SNP and the Conservatives who said it was his party which was inflaming divisions.

Angela Crawley, SNP spokesperson for equalities and candidate for Lanark and Hamilton East, said: “Only a vote for the SNP is a vote to escape Brexit, and to put Scotland’s future in Scotland’s hands – not Boris Johnson’s – by giving people the choice of a better future with independence.

“The reality is that Gordon Brown would rather see Scotland dragged out of the EU against our will, with all the huge damage that would do, than see us become an equal, independent country. That attitude is why so many people are deserting Labour across Scotland.”

Scottish Conservative MSP Annie Wells said: “It’s a bit rich for Gordon Brown to make these remarks when his party wants to drag us back to more division and chaos.

“Labour wants to hold another Brexit referendum and allow the SNP to stage indyref2 – that will only prolong the pain.”

Gordon Brown warns of years of division after Brexit and rise of nationalism