An anti-fascist movement has expressed deep concern after learning that Ukip voted to ban its members from joining the party.
Members brought a motion to last weekend's UKIP national conference to proscribe HOPE not hate. Ukip also proscribe the British National Party.
"It's incredible that a party that's desperately denying claims that it is racist bans membership from Britain's largest anti-racist organisation," Hope Not Hate's Nick Lowles said.
"UKIP claim HOPE not hate is an extremist organisation, putting us on par with the fascist BNP. This is clearly ridiculous.
"The reality is that over the last few months we have begun to put UKIP under the microscope. We've exposed the racist rantings of some of their key organisers and councillors. Just in the latest fortnight we have exposed Farage's speechwriter and press spokesperson for using insulting and abusive language mocking people with disabilities and the NF past of a Thurrock UKIP councillor, who told us when we confronted him that he saw in UKIP the same things he saw in the NF.
"We have got under UKIP's skin and they don't like it. But rather than deal with their own racists they are trying to silence us."
But the party's spokesman said that the motion had been brought by party members and "that's what happens when members have a free say on what policies the party has.
"The reality is that we entirely support the anti-fascist, anti-racist principles of Hope Not Hate," he told HuffPost UK. "But they are ceasing to become an anti-fascist party and become an anti-Ukip party. They are attacking our policies which have nothing to do with racism or fascism."
In a formal statement, the party said: “Hope not Hate is a non-transparently funded organisation who has taken it upon themselves to launch a campaign of harassment and slur against UKIP. It is no surprise that a vote of the membership of UKIP decided to proscribe it as extreme. In its behaviour recently it has shown itself to be so.
“UKIP share their stated aims in combating racism and fascism, and will not have either in the party. Indeed we entirely support them in their campaign against the Government’s Lobbying Bill and believe that they have, if they stuck to their stated aims, a useful role to play.”
Lowles denied his group was anti-Ukip, but said it was simply concerned about extreme elements in the party. "We do not take a position on membership of the EU," he said in a blog on the organisation's website.
"We do, however, oppose political parties who whip up anti-immigrant prejudice through scaremongering and playing on racist fears. This not only leads to increased racism in our communities but risks pushing the main parties to the right on immigration and multiculturalism.
"UKIP might proscribe us but they will not silence us."
In April, Hope Not Hate surveyed its supporters whether they should start campaigning against Ukip. Over 1,800 replied, with two thirds in favour.