Former English Defence League leader Tommy Robinson has been appointed as an adviser to Ukip leader Gerard Batten (David Mirzoeff/PA)
But Mr Farage said Mr Batten was taking the eurosceptic party in a “shameful” direction.
“I was always insistent as leader that nobody could join us if they’d been members of the EDL or the British National Party,” Mr Farage told the Press Association.
“I wanted to make tough arguments about illegal immigration, what was happening in the Mediterranean and all the rest of it without any taint of racism or Islamophobia.
“I can’t believe that the current Ukip leader wants to welcome in the founder of the EDL, a man who’s done four prison sentences, lives under a pseudonym and wherever he goes there’s violence.
“The whole thing is crazy. And this at the very moment when Brexit is in a right mess, when both Tories and the Labour Party are breaking their promises to the electorate.
“There’s a massive opportunity for Ukip, a big opportunity for millions to say to the Government Brexit is not going the right way, and all Gerard Batten wants to do is get this, frankly, thug involved with the party.”
Mr Farage said he was concerned a pro-Brexit rally Mr Batten and Mr Robinson are planning for December 9 in London could undermine efforts to defeat Theresa May’s Withdrawal Agreement in a Commons vote in the following days.
“It’s a march through Westminster,” said Mr Farage.
“I know what will happen. It will be full of skinheads and people with tattoos to the eyeballs, they’ll all be drunk before they get there, there’ll be punch-ups and God knows what.
“And the next day, it’s the vote on the Brexit thing.
“And this is how Brexit will look, it’ll look like a bunch of far-right football thugs, and I am absolutely disgusted by it.
“I’ve held my silence as a former party leader until now but we now have to get rid of this bloke as leader because he’s not just damaging Ukip, he’s damaging Brexit.”
Mr Farage did not rule out returning as a candidate for the Ukip leadership himself but said it was “not top of my bucket list” after having already devoted 20 years to the party.
“If it had to be done, I’d consider it,” he told PA.