The economic case for the UK to leave the European Union is "absolute nonsense", says Sir John Major.
The former Conservative Prime Minister told BBC Radio 4's Today Programme that the UK Independence Party (Ukip), which has anti-mass immigration and Eurosceptic policies, is not a "tolerant party".
Major also divulged that he did not think the organisation's "appeal is likely to continue for a very long time".
The comments come after the right-wing party won 24 seats in the 2014 EU Parliament Elections, putting Ukip at the top of the poll with a vote share of 27.5%.
Major, who was leader of the Conservative Party between 1990 and 1997, also said that the Prime Minister David Cameron was "absolutely right" to pledge a referendum on the UK's membership of the EU in 2017 if his party wins the next general election.
More than 67% of voters backed the UK joining the European Economic Community (EEC) – a precursor to the EU – in 1975.
Cameron has sought to limit the EU's powers and recently attempted to block the appointment of an arch-federalist to the job of European president.
However, his party lost 7 MEPs (down to 19) in the May elections and the organisation's vote share fell by 3.8% to 23.9% when compared to the previous election.
The official opposition, Ed Miliband's Labour Party, came second in the election with 20 MEPs.
But the Liberal Democrats fared worse out of the four main parties as Nick Clegg's party lost all but one of its MEPs.
The election result prompted to calls for Clegg to go and former Liberal Democrat peer Lord Oakeshott leaked a poll of voters in Clegg's Sheffield Hallam constituency, which predicted that the party leader would lose his seat in 2015.
Oakeshott, a close ally of the Business Secretary Vince Cable, admitted to plotting against Clegg in a sensational resignation letter and urged party activists to fight for a new leader.