UKIP leader Nigel Farage has described protesters who besieged him in an Edinburgh pub as "fascist scum".
Mr Farage had to be escorted from the Canons' Gait pub in a police van after angry confrontations on Thursday.
He told BBC Scotland the incident was deeply racist and displayed a total hatred of the English.
Mr Farage called on Scottish National Party leader Alex Salmond to condemn the behaviour. The SNP said the UKIP leader had "lost the plot".
Mr Farage hung up during a telephone interview with the Good Morning Scotland programme on BBC Radio Scotland after being pressed about his lack of knowledge of Scottish politics and the low level of support for his party north of the border.
He later described the interview as "insulting".
First Minister Alex Salmond said that Mr Farage's accusation of a "hate campaign" from the BBC during the radio interview showed it would be a "great mistake" to take "somebody of that mentality with any degree of seriousness".
Mr Salmond added: "We can frankly do without UKIP, who dislike everybody and know absolutely nothing about Scotland."
When asked if he condemned the demonstration against Mr Farage, the first minister said: "If there's been any law-breaking - and that's yet to be established - then obviously we condemn that, as we always do in Scotland, but you've got to get things into context.
"A student demonstration isn't the Dreyfus trial."
Mr Farage was in Edinburgh to launch his party's Scottish campaign following recent electoral gains in England.
Police said two men had been arrested following the protest.
Speaking to the Good Morning Scotland programme, Mr Farage said: "If this is the face of Scottish nationalism, it's a pretty ugly picture."
He added: "The anger, the hatred, the shouting, the snarling, the swearing was all linked in to a desire for the Union Jack to be burnt."
The UKIP leader said the demonstrators did not represent Scotland and dismissed suggestions his party was an irrelevance north of the border.
"The fact that 50 yobbo fascist scum turn up and aren't prepared to listen to the debate, I absolutely refuse to believe is representative of Scottish public opinion," Mr Farage said.
He said he had heard before that some parts of Scottish nationalism were "akin to fascism" but "yesterday I saw it face-to-face".
Mr Farage also told BBC Radio Four's Today programme that the protesters were "filled with a total and utter hatred of the English".
"For some reason the British media has never talked about the excesses of Scottish nationalism and how deeply unpleasant they can be," he said.
Mr Farage did not suggest this was anything to do with the SNP as a party.
But he added: "These people were supporters of Scottish nationalism, virulently opposed to the English, all sorts of suggestions as to what we could do with the Union Jack and I would like to hear Alex Salmond come out and condemn this sort of behaviour. I challenge him today to do that."
He said: "If anybody from UKIP says anything on Facebook that is in any way homophobic or mildly racist you guys jump down my throat and demand I condemn them and expel them from the party, which of course I do. It is about time Scottish nationalism was put under the same level of scrutiny."
An SNP spokesman said: "Anyone who heard the interview with Nigel Farage on BBC this morning would have thought he has completely lost the plot.
"He accused the BBC of hatred when under pressure and panicked during an interview. Nothing he says can be treated with a shred of credibility and his partners in the No campaign should be embarrassed about his behaviour."
A spokesman for the Radical Independence Campaign, who helped organise the demonstration in Edinburgh, said there had been "no anti-English protest".
He added: "For Farage to make such a claim is risible: it is UKIP who are stoking division.
"This was about challenging someone whose party has been spouting racist, sexist and homophobic bile and gone unchallenged for months.
"Everyone who opposes the politics of fear and division should unite against UKIP - whether you live in Scotland or England."
John Martin, president of the Edinburgh College Students' Association, which also took part in the protest, said: "We organised yesterday's protest against Farage out of a belief that UKIP's policies are fundamentally rotten.
"Their headline five-year immigration freeze is not only completely disconnected from reality, but is a policy that neither the people of Scotland nor the rest of the United Kingdom would stomach.
"His regressive and repugnant ideology is not far removed from that of the BNP - just dressed in a better-fitting suit."
The Scottish Conservatives condemned the protesters who heckled Mr Farage, and criticised the first minister for his subsequent comments.
Alex Johnstone MSP said: "Alex Salmond is the last person who should be coming out and condemning Nigel Farage and his comments today are total hypocrisy.
"Let's not forget this is the same first minister who branded a BBC executive a 'Nazi official' for not being allowed to act as a rugby pundit on TV."
He added: "Yesterday's abuse handed out by separatists was another shameless example of the lengths they will go to hijack the independence debate in Scotland."