Just days before the European elections, Ukip has been embroiled in yet another scandal after one of its candidates suggested the three main political parties and those who support them should be hung for treason.

In a letter to voters dated 15 May, Gordon Ferguson stated: “The Lib-Lab-Cons have conspired with a foreign power, the EU, and are all thereby guilty of treason. They have sold Britain, which is the 5th largest economy, illegally into increasing slavery outside the EU dictatorship.

“Those responsible should be hung by the neck until dead (but Blair illegally changed the penalty to save his own neck).”

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Later in the letter Mr Ferguson said: “If you vote for any of the three Lib-Lab-Con parties you will be aiding and abetting them and you will also be guilty by association of treason against our nation.”

Mr Ferguson, who is running for Cambridge ward in Southport, Lancashire, suggested that the three main political parties are “collaborating with large corporations such as the banks, utility companies and local councils, all in order to defraud and again impoverish the people”.

And he called them “deceitful liars”.

Shape Created with Sketch. Ukip gaffes and controversies Show all 18 left Created with Sketch. right Created with Sketch. Shape Created with Sketch. Ukip gaffes and controversies 1/18 European elections poster Party's latest EU election posters branded 'racist' and compared to BNP campaigns Rex 2/18 Farage 'car-crash' interview Ukip spin doctor forced to intervene as Farage falters in disastrous radio interview 3/18 Neil Hamilton Picture Exclusive: The year is 1998. The venue is a Springbok Club meeting. The flag is a symbol for white supremacists in South Africa. And the speaker is Ukip’s deputy chairman, Neil Hamilton 4/18 Kerry Smith Kerry Smith resigned as would-be MP for South Basildon and East Thurrock after it emerged he had mocked gay party members as “disgusting poofters”, joked about shooting people from Chigwell in a “peasant hunt” and referred to someone with a Chinese name as a “Chinky bird” PA 5/18 Natasha Bolter Former Ukip member Natasha Bolter was suspected of not having the teaching qualifications she professed to, only days after it was revealed that claims of her having attended Oxford University were also false PA 6/18 Ukip Calypso song Mike Reid released a single in praise of UKIP trying to control the UK's borders, only to withdraw the single after being accused of racism for singing in a Jamaican accent 7/18 Janice Atkinson Janice Atkinson, Ukip's South East chair, pictured by protesters while campaigning in Ashford, Kent with local party chair Norman Taylor Facebook/Maria Pizzey 8/18 Ukip cancels Freephone Ukip cancels Freephone number after protesters repeatedly called to push up costs Getty Images 9/18 Farage 'car-crash' interview Mr Farage appeared to be caught out on a number of issues, from Romanian neighbours to people speaking foreign languages on the train 10/18 Ukip employs illegal immigrants Ukip criticised after European election candidate found employing illegal immigrants AP 11/18 Magnus Nielsen Ukip candidate: 'Take away the right to vote to improve election turnout' Getty Images 12/18 Poster model A “British builder” portrayed in a Ukip poster accusing EU workers of taking UK jobs turns out to be an Irish actor - aka a migrant worker 13/18 'Arrest protesters' Ukip called for police to arrest protesters ‘who call us fascists’ ahead of showdown with anti-fascist groups in Brighton 14/18 London Live make-up Ukip's Nigel Farage reportedly refused to go on London Live 'without professional make up-artist' Reuters 15/18 Andre Lampitt Ukip forced to suspend the "poster boy" of its European election broadcast, after it was revealed he had posted a series of vile racist comments on Twitter 16/18 Expenses Nigel Farage says he is taking taking legal advice over “outrageous” allegations that he is responsible for more than £50,000 of “missing” EU funding that was paid directly into his personal bank account 17/18 Have I Got News For You Nigel Farage appears in Have I Got News For You, spends the entire episode being ridiculed over expenses and party 'fruitcakes' BBC 18/18 Anti-gay comments Local branch chairman for Ukip defends a party's councillor candidate Douglas Denny who called gay people “abnormal” and said he wished “they stop trying to ram it down my throat”, all while discussing whether the word “sodomite” should be used 1/18 European elections poster Party's latest EU election posters branded 'racist' and compared to BNP campaigns Rex 2/18 Farage 'car-crash' interview Ukip spin doctor forced to intervene as Farage falters in disastrous radio interview 3/18 Neil Hamilton Picture Exclusive: The year is 1998. The venue is a Springbok Club meeting. The flag is a symbol for white supremacists in South Africa. And the speaker is Ukip’s deputy chairman, Neil Hamilton 4/18 Kerry Smith Kerry Smith resigned as would-be MP for South Basildon and East Thurrock after it emerged he had mocked gay party members as “disgusting poofters”, joked about shooting people from Chigwell in a “peasant hunt” and referred to someone with a Chinese name as a “Chinky bird” PA 5/18 Natasha Bolter Former Ukip member Natasha Bolter was suspected of not having the teaching qualifications she professed to, only days after it was revealed that claims of her having attended Oxford University were also false PA 6/18 Ukip Calypso song Mike Reid released a single in praise of UKIP trying to control the UK's borders, only to withdraw the single after being accused of racism for singing in a Jamaican accent 7/18 Janice Atkinson Janice Atkinson, Ukip's South East chair, pictured by protesters while campaigning in Ashford, Kent with local party chair Norman Taylor Facebook/Maria Pizzey 8/18 Ukip cancels Freephone Ukip cancels Freephone number after protesters repeatedly called to push up costs Getty Images 9/18 Farage 'car-crash' interview Mr Farage appeared to be caught out on a number of issues, from Romanian neighbours to people speaking foreign languages on the train 10/18 Ukip employs illegal immigrants Ukip criticised after European election candidate found employing illegal immigrants AP 11/18 Magnus Nielsen Ukip candidate: 'Take away the right to vote to improve election turnout' Getty Images 12/18 Poster model A “British builder” portrayed in a Ukip poster accusing EU workers of taking UK jobs turns out to be an Irish actor - aka a migrant worker 13/18 'Arrest protesters' Ukip called for police to arrest protesters ‘who call us fascists’ ahead of showdown with anti-fascist groups in Brighton 14/18 London Live make-up Ukip's Nigel Farage reportedly refused to go on London Live 'without professional make up-artist' Reuters 15/18 Andre Lampitt Ukip forced to suspend the "poster boy" of its European election broadcast, after it was revealed he had posted a series of vile racist comments on Twitter 16/18 Expenses Nigel Farage says he is taking taking legal advice over “outrageous” allegations that he is responsible for more than £50,000 of “missing” EU funding that was paid directly into his personal bank account 17/18 Have I Got News For You Nigel Farage appears in Have I Got News For You, spends the entire episode being ridiculed over expenses and party 'fruitcakes' BBC 18/18 Anti-gay comments Local branch chairman for Ukip defends a party's councillor candidate Douglas Denny who called gay people “abnormal” and said he wished “they stop trying to ram it down my throat”, all while discussing whether the word “sodomite” should be used

Mr Ferguson, who runs a care home for the elderly, told The Telegraph that he believed in the death penalty for those he considered traitors to Britain – the punishment was abolished in 1998.

“That is the old English law, is it not?” he said.

Asked whether he thought the same penalty should apply to those who voted for the so-called traitors, he replied: “If that is the law of the land, that should apply.”

“I want them to think about the implications of them supporting an organisation that is not working in the interests of the British people.”

But he went on to say: “By being so forthright, maybe that was not wise. I would hate to be an embarrassment to Nigel Farage. I have the greatest respect for him.”

Nigel Farage's anti-EU party has come under increasing scrutiny in the lead-up to the elections on Thursday, following a series of embarrassing gaffes.

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Mr Farage has complained that the media focuses too much on the “idiots” in the party.

Earlier this month he said: “I am not saying we haven't had our problems, we have.

“Every party has these kinds of problems but there is a completely disproportionate media spotlight on what goes wrong in Ukip compared to the others.”

And on Saturday the Ukip leader issued a statement denying that he expressed racist sentiments in an interview with LBC presenter James O’Brien on Friday.

In the statement he said: “Ukip will never allow the false accusation of racism levelled by a politically correct elite to prevent the raising of issues that are of concern to the great majority of the British public.”

Mr O’Brien had questioned Mr Farage, whose wife is German, on his claim that he would feel uncomfortable if a group of Romanian men moved in next door, pressing him to say whether he ”would feel the same about a group of German children“, asking ”what's the difference?“

Mr Farage replied: "I think you know the difference. We want an immigration policy that is not just based on controlling not just quantity but quality."

In the statement he appeared to reinforce these comments. He said: "Police figures are quite clear that there is a high level of criminality within the Romanian community in Britain. This is not to say for a moment that all or even most Romanian people living in the UK are criminals.

“But it is to say that any normal and fair- minded person would have a perfect right to be concerned if a group of Romanian people suddenly moved in next door.”

However, despite the controversies, Ukip is set for landmark win at the EU elections, according to a poll by The Independent on Sunday.

The ComRes poll gives Ukip its highest lead in a European elections survey. Among those who are certain to vote, Ukip is on 35 per cent, 11 points ahead of Labour, on 24 per cent, with the Conservatives down two points from the last ComRes poll earlier this month, at 20 per cent.

The Green Party has pushed the Liberal Democrats into fifth place and is up two points to 7 per cent, while Nick Clegg's party is down two to 6 per cent.

The Independent was unable to reach Mr Ferguson.

The Ukip press office said they would not pass on Mr Ferguson’s contact details and declined to comment further on the issue.