The Brexit campaign won "because they were spreading fear against immigration, against the diversity of the British community", a survivor of the Anders Breivik massacre has claimed.
Bjorn Ihler, who described the moment Breivik aimed his gun at him and fired during the massacre in Norway in 2011, only to miss, said that "by spreading that fear they also created a breeding ground for far-right extremist communities in Britain.
"We see this all the time across Europe and the world, that politicians are using various narratives to divide us ... it's extremely effective from a political point of view - that's why the Brexit side won," he said.
Mr Ihler, a young leader in Kofi Annan's Extremely Together initiative, works in Norway and Europe to identify individuals at risk of becoming radicalised and to counter extreme right-wing narratives - something he has been doing since seeing many of his friends gunned down by Breivik, who blamed Muslims, immigrants and feminism for a "European cultural suicide".
"If you look to western Europe, and Britain specifically right now, the stories you are being told is that immigration is bad, they are coming here to take over the country and ruin what Britishness is," he said.
"What we do is prove that those stories are wrong, essentially," Mr Ihler said about his work with Extremely Together.
"Let's sit down, have a cup of tea and get to know the person before we believe in the stories we are being told about each other. Because we are far too often being told to be afraid of each other than to be united. So we need to start telling the story of being united and that's what Extremely Together is all about."
Mr Ihler said at the One Young World Summit in Ottawa, Canada, that he believes "integration" is important, but that local communities do not play their part in aiding it.
"I think in those communities it is also important for both immigrants and ... 'not immigrants' to meet in the middle, to reach out to each other.
"We far too often speak about integration as something that has to come from the immigrant's side, what we fail to realise quite often is that integration is something that also has to have a part played by the local side. So, in integration, it's equally important for the community that's receiving someone to be integrating people," he said.
Reports suggested that following Brexit there was a "surge" in racism and xenophobia, while Labour MP Jo Cox died in the street in the lead-up to the vote in an apparent right-wing attack.