The party said the Conservative candidates they will not campaign against are Philip Davies in Shipley, Douglas Carswell in Clacton, Janice Small in Batley and Spen, Alex Story in Wakefield and Philip Hollobone in Kettering.
Neither will they challenge independent Bob Spink in Castle Point.
However, Lord Pearson stressed that none of the candidates from other parties had asked for UKIP's help.
Deputy leader David Campbell Bannerman denied that UKIP was a "single issue party" but said that Europe was "central to this domestic election".
Mr Campbell Bannerman told the BBC: "We have policies in all areas, including animal welfare, pubs etc, right across the board - and that's our manifesto being launched today."
He told a press conference that the UK could establish a free trade area with the Commonwealth to establish links with "our kith and kin".
The party's campaign slogan in its bid for a Westminster breakthrough is "Straight Talking".
They promise a new flat tax at 31%.
We can't have our own immigration and asylum policy if we remain members of this European Union
UKIP also want a five year freeze on new immigrants settling in Britain and a ban on wearing the burka in public buildings and certain private buildings, and boot camps for young offenders.
In addition to the promised savings UKIP say they could make by leaving the EU, they have also pledged to immediately implement £50bn a year of cuts drawn up by the Taxpayers' Alliance which campaigns for greater government efficiency.
These include abolishing Sure Start, the Building Schools for the Future programme, health service IT projects and ID cards, while halving public spending on consultants, reducing civil service staffing by 10%, cutting the culture, media and sport budget and freezing grants given to Scotland, Wales and Northern Ireland.
Free TV licences for the elderly, student loan subsidies, child benefit and child trust funds would also go.
Additionally, UKIP would simplify tax and welfare by removing means testing from pensions, which they say would mean an £8bn saving.
The party's former leader Nigel Farage is standing in Buckingham against the Speaker of the House of Commons, John Bercow.
Mr Farage said the election campaign so far had been a "piddling irrelevance" and the mainstream parties had not addressed the reality of the UK's economic problems.
"It really is time for some straight talking," he added.
"We are skint. We need some massive cutbacks in the public sector.
"We can't have our own immigration and asylum policy if we remain members of this European Union."
Other candidates will include the boxing promoter Frank Maloney in Barking, Lord Pearson's wife Lady Pearson in Kensington and the former Conservative MP Christopher Gill in Ludlow.
In the 2009 European Parliament elections they beat Labour to second place, winning 13 seats, but UKIP expelled MEP Nikki Sinclaire in March after she refused to be part of its multi-national group.
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