Ukip leader Nigel Farage has said there is "something unpleasant going on" in Scotland after a chaotic day's campaigning, with a senior party figure claiming there is a "problem with democracy" north of the border.
Mr Farage went north on Tuesday to campaign for his candidate in the Aberdeen Donside Scottish Parliament by-election, but was forced to repeatedly change his plans after a proposed press conference venue and a meeting with a senior councillor was cancelled.
He was due to have tea with Aberdeen Council deputy leader Marie Boulton in the city townhouse, but it was cancelled at the last minute. Ukip blamed the cancellation on threats of "violent" protests.
Earlier, they were forced to change their press conference venue following a late cancellation by the Marriott Hotel, in Dyce, allegedly following threats by a group called the Aberdeen Anti-Fascist Alliance.
Ukip president in Scotland Lord Christopher Monckton said there is a problem with democracy in Scotland, a place where only "the party line" is permitted.
This latest visit comes a month after Mr Farage was hounded out of a pub by protesters during an earlier campaign trip to Edinburgh on 16 May.
The by-election takes place on Thursday. The seat was made vacant by the death of SNP MSP Brian Adam.
Mr Farage said: "It was very sweet of (Ms Boulton) to ask me but obviously there has been a lot of pressure brought to bear.
"There is this narrative, and we saw it in Edinburgh a month ago, and I also saw it on Question Time last week not just from the SNP but from a very senior journalist, saying that Ukip's voice shouldn't be heard here.
"So every attempt is being made to stop us from speaking.
"I've never come across anything like it in all of my life anywhere in Britain, Europe or the world for that matter.
"The idea that you can disagree with someone's point of view but you have it out and debate these things and let the public judge is what the democratic process is all about.
"There is something quite unpleasant going on.
"I was going to go for tea, which is a very civilised gesture and very much in line with the hundreds of emails I've had since Edinburgh saying: 'Please don't judge Scotland on the behaviour of a few students'.
"Clearly the invitation was issued but some pressure has been brought to bear, from whom I don't know.
"Obviously phone calls have been made, representations have been made and the person now feels uncomfortable.
"I think frankly the police are a little bit nervous, because some of the things that happened in Edinburgh were really quite nasty."
Lord Monckton said: "Police advised against the meeting at the townhouse. That of course indicates a problem with democracy in Scotland.
"Only one view - the party line - is permitted and anyone who wishes to go in another direction is threatened in the street, menaced, attacked and now we have a meeting cancelled because people wish to stop it by violence."
Regarding the Marriot cancellation, he said: "We had agreed a very competitive price and we were getting two rooms to dine in and hold a press conference.
"However, when I then tried to telephone to ensure everything was confirmed my calls were not returned, and when I eventually managed to get through I was told another booking had offered more money.
"What we think happened was group calling themselves the Aberdeen Anti-Fascist Alliance had threatened to cause a disturbance at the press conference.
"We think the Marriott behaved in a manner that fell short of what we would regard as professional."
An Aberdeen City Council spokesman said: "This was a private meeting arranged between an elected member and Mr Farage's team.
"The meeting was not, in any shape or form, an Aberdeen City Council meeting."