EU Chief Donald Tusk has slammed Nigel Farage as a hypocrite for refusing to back a second referendum - when he already called for one.
Mr Farage had warned MEPs that he would be back to haunt them if Brexit delays saw the UK take part in EU elections.
But Mr Tusk said Farage's argument against a second referendum rang hollow because he hadn't accepted the result of the UK's first referendum in 1975.
Mr Tusk said: "Mr Farage, you have presented passionate arguments against a second referendum.
"But the truth is that the second referendum took place in 2016 because the first one took in 1975.
"It was you who thought three years ago that it was possible to organise a referendum to invalidate the previous one, then please be consistent also today.”
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But Brexit architect Nigel Farage urged MEPs not to extend article 50 and accused Mr Tusk for trying to undermine democracy in the EU.
He said: "Do you really want me back in this place?"
Mr Tusk has said that the almost six million people who have signed a petition calling for Britain to stay in the EU must not be "betrayed".
Speaking to the European Parliament, Mr Tusk, who is head of the European Council called on the EU to be open to a long Brexit extension and not to ignore the "increasing majority" who wanted to remain in the European Union.
But Mr Tusk said the UK risked looking like mythological sphinxes guarding ancient tombs - trapped by a riddle.
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Mr Tusk said: "You cannot betray the six million people who signed the petition to revoke Article 50, the one million people who marched for a People's Vote, or the increasing majority of people who want to remain in the European Union.
"I told some of you that if you compare Great Britain to a sphinx then the sphinx would seem to me an open book. We will see in the course of this week how this book will speak."
