Nigel Farage told fellow MEPs "you're not laughing now" as he was barracked and booed at an emergency meeting of the European Parliament to discuss Brexit.
The Ukip leader accused them of being "in denial" about the euro crisis, immigration and the imposition "by stealth, by deception, without ever telling the truth" of a political union.
Offering a tongue in cheek "thank you for the warm welcome", he told them: "When I came here 17 years ago and said I wanted to lead a campaign to get Britain to leave the European Union you all laughed at me.
"Well I have to say you're not laughing now are you?"
As the session was disrupted by constant shouts of dissent, Parliament president Martin Schulz was forced to intervene, warning members that "one major quality of democracy is that you listen to those even if you don't share their opinion".