The group is targeting seats where the party is standing and says there are 15 where they 'could win or where it is going to be a very tight race'.

Those include Dudley North, where West Midlands UKIP MEP Bill Etheridge is standing against Labour's Ian Austin. Mr Austin's majority is just 649 votes.

Also on the list is Cannock Chase, where the Tories are defending their biggest swing from Labour at the last election.

The party also thinks UKIP has a good chance in Labour-held Walsall North and in Tory Wyre Forest.

UKIP has condemned the campaign and accused Hope Not Hate of 'scaremongering'.

Mr Etheridge and fellow MEP James Carver, the party's candidate for Stourbridge, said the group was a 'negative and divisive and intimidatory force in British politics that is now moving to deliberately target UKIP, its supporters and its elected officials to stop democracy'.

Mr Carver said: "Hope Not Hate is about hate not hope. It uses its negative messages, and indeed bare-faced lies, to target the rise of UKIP which is a positive force in British democracy and politics.

"We believe in standing up for Britain and its interests. Hope Not Hate's own negative messages and campaigning will not hamper our own positive efforts to stand up for this country and local communities. UKIP is a non-racist, non-sectarian party that believes in freedom, fairness and democracy."

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Mr Etheridge added: "I call on senior Labour figures to denounce Hope Not Hate and its messages of fear and prejudice.

"It is appalling that this band of state-sponsored rabble rousers have the support of Labour and trade unions. They will not hamper my campaign in Dudley North and I promise to counter their smears and lies. Labour should condemn Hope Not Hate."

Although Mr Etheridge said they were 'state-sponsored' the group says it received a grant for £60,000 from the Department for Communities and Local Government to undertake anti-racist community work in four areas of the country and it was a one-year project which ended in 2012.

On it website Hope Not Hate said: "Hope Not Hate has one principle goal in the forthcoming General Election – to limit the success of the UK Independence Party (UKIP).

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"We believe that UKIP has become a radical right, anti-immigration party. Every success it achieves only further encourages racist scaremongering, intolerance and hatred.

"More fundamentally, we believe that UKIP is part of a trend of populist right-wing parties rising across Western Europe. The policies of these 'parties of prejudice' are challenging the very notion of a free and fair, and multicultural society, where people of different backgrounds and faiths can live together peaceably."

A spokesman added: "Instead of making wild allegations and playing the victim card, UKIP would be wise to concentrate on getting its own house in order. Not a day goes by without leading UKIP members, supporters, candidates or elected officials making extreme, offensive comments that belie its 'party of the people' message.

"Whether that be 'gay floods', UKIP councillors stating on national TV that they don't like 'negroes', or multiple candidates being exposed on social media for sharing far-right material, is it any wonder the party is struggling to attract the under-50s? It's all very well to claim to be 'got at', but the stark truth is that UKIP attracts a lot of people with very extreme views: perhaps they should explain to us all 'why'? If you want to aim for national office, you have to expect scrutiny. Instead of crying foul, get your house in order."