NIGEL Farage returns to Edinburgh today suggesting a repeat of his "anti-English" treatment there would expose a streak of racist hatred in Scotland.

The Ukip leader expressed confidence his party would finally break through in Scottish politics at the May 22 European elections, insisting it would shake up the independence referendum debate and boost the No campaign.

But while polls in England give Ukip as much as 31% of the vote, in Scotland, where it still has no representation, its highest rating has been 18%, in a small-sample poll.

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A year ago Mr Farage was forced to lock himself inside the Canons' Gait pub on the capital's Royal Mile as protestors chanted "go home to England" and "racist Nazi scum". Police had to intervene.

He claimed there were now "hate groups … all over the UK" that had decided Ukip was a racist party, an assertion he dismissed as "ludicrous".

"You can call us what you like; you can disagree with everything we stand for, and that's fine; but if you think you can tag this racist label on us, you've chosen the wrong target," he said.

Asked if he expected another rough ride in Edinburgh, he replied: "I don't know what will happen. I suspect, from the perspective of the Scottish Nationalists, that's probably the worst thing that could happen, because what we saw last year in the streets were some basically anti-English [protests]. Talk about racism - that is what was being expressed, hatred."

A Police Scotland spokeswoman said she could not comment on whether special measures would be taken for his return to the city for a Ukip rally, but the force would "supply the appropriate police resource as required."

With the European poll less than two weeks off, the Ukip leader suggested the last thing the First Minister wanted was for anti-EU Ukip to win one of Scotland's six European parliamentary seats.

"Mr Salmond is hoping Ukip do not nudge over the line on May 22 because he knows as soon as Ukip is there the whole Scottish debate changes, the word independence starts to mean something different in the context of the EU," he said. "It will expose the fact that you are not having an independence referendum. The whole thing is a misnomer because the package is 'say No to Westminster and Yes to Mr Van Rompuy'."

Mr Farage said he was "very confident" David Coburn, Ukip's lead Euro candidate, would win a seat in Scotland and make a political breakthrough.

Asked if this would boost the No campaign, he replied: "It would, yes. Whatever you think of Brussels and the EU set-up, you can't be an independent country and a member of the EU, period. That voice has not been heard in Scotland. I came up last year to make that point and was shouted down. Once we have someone elected, you can't stop that from being out there."

Mr Farage also suggested if Ukip won a seat north of the Border, it would counter the claim that Scottish values were different from English ones and change the tenor of debate in Scotland.

Recently, Mr Salmond raised eyebrows by confessing to a "sneaking regard" for the Ukip leader for having "influence beyond his significance".

"He's a good operator," Mr Farage said of Mr Salmond. "He's terribly good at what he does. If he wants to say that, that's jolly nice."

Ruth Davidson, the Scottish Tory leader, suggested the Ukip leader was trying to be an anti-Westminster "bellicose Nationalist voice", but he insisted the Tories were irrelevant and would be gone in a few years.

"We will become an alternative voice in Scottish politics and while we are not very big yet in Scotland, what you have seen in much of the north of England is us becoming the opposition to the Labour Party," Mr Farage said.

Last night Scottish Liberal Democrat leader Willie Rennie said Mr Salmond must "call off the dogs" for Mr Farage's visit. He said there must be no repeat of last year's trouble and the First Minister must "stand up for free speech".

Mr Rennie said he he was "horrified" by the sight of the Ukip leader being "chased out of Edinburgh by aggressive independence supporters".

He declared: "His unpleasant and dishonest agenda will be defeated by argument, not aggression."

He added: "Last year, we saw self-proclaimed anti-racist campaigners tell an Englishman to get back to his own country. Anti-racists turned racist but were too ignorant to notice. So the First Minister must make clear that aggressive and confrontational behaviour has no place in any debate."

SNP MSP Christian Allard said: "Nigel Farage of course has every right to free speech, and the First Minister has never suggested otherwise - fortunately, the more that the people of Scotland hear of Farage and his party, the less they like their message."