Nigel Farage has said violence on the streets could be the "next step" if immigration is not controlled.
The Ukip leader told the BBC said it was "difficult to contemplate" it happening in Britain, but added "nothing is impossible".
“It’s legitimate to say that if people feel they’ve lost control completely, and we have lost control of our borders completely as members of the EU, and if people feel voting doesn’t change anything, then violence is the next step," he said.
Labour shadow cabinet minister John Ashworth reacted to Farage's comments. "Hitler, violence on the streets - what a pair of charmers Boris & Farage are. Every day case for remaining in EU gets stronger," he said on Twitter.
On Tuesday, Farage was slapped down for claiming Labour promoted immigration “to rub our noses in diversity” during an impassioned hustings before the EU referendum.
The Ukip leader was speaking in a panel debate hosted by The Mirror newspaper, which also featured Labour Shadow Chancellor John McDonnell and Lord Peter Mandelson, the former Labour Cabinet minister and EU commissioner.
At one stage, Farage hit out at the Labour Government’s “deliberate policy” of championing immigration that has now “hurt working people” - but was accused of “dog-whistle” politics and offending black writer and fellow panelist, Dreda Say Mitchell.