Labour have turned the Oldham West and Royton by-election nasty by calling Ukip 'evil', according to Nigel Farage. The Eurosceptic firebrand, speaking exclusively to IBTimes UK, made the remarks after shadow chancellor John McDonnell attacked the party at a fundraiser in the Greater Manchester seat.

"We can not allow what I think is an evil force within our society – that divides society often on the basis of race, often on the basis on some of the crudest policies that you can imagine any political party advocating," The Spectator reported the left-winger saying.

"We cannot allow them to get any form of a toehold within our political system and that's why it's about defeating them but more importantly, defeating them — a clear contrast in terms of a sincere, local committed socialist candidate."

Farage, who warned that by-elections could be "very rough and dirty businesses", said: "When John McDonnell describes Ukip as an evil force in society, that's quite nasty, yeah."

The Ukip leader's remarks come ahead of the 3 December vote, which was triggered after former Labour MP Michael Meacher passed away. Meacher beat Ukip into second place at the general election with his majority almost hitting 15,000.

Oldham Council leader Jim McMahon has been selected as Labour's candidate. But with Jeremy Corbyn's leadership issues in Westminster, some reports have claimed that his party's majority could be reduced to a few thousand at the by-election as Ukip hopeful John Bickley plans to take advantage of Labour's public split.

"It's going to be close, it could well be within a few hundred votes," Farage added. "The key factor on the day will be turnout – the weather forecast is dire, and have people got the energy to go down to the primary school and vote. My feeling is that the Ukip voters are very keen, they believe in what we are trying to do, and a lot of Labour voters, who have been Labour families for a hundred years, are they going to bother? I don't know, we will find out on Thursday night."

The Eurosceptics have launched their own personal attacks against the Labour leader by calling him a "security risk" and highlighting his previous comments on the UK's nuclear deterrent Trident, along with other defence polices.

"I would honestly say to you that 40% to 50% of people who come from traditional Labour families are deeply concerned by Corbyn's leadership of the Labour Party," Farage said. "There are lots of reasons for it, but the key is when he was asked the question 'if there is a Kalashnikov-totting terrorist in a shopping centre shooting people, should the police shoot to kill?' and he hesitated and people are very concerned about that."