Media playback is unsupported on your device Media caption "Disadvantages of remaining in the EU outweigh any advantages"

Former Chancellor of the Exchequer Lord Lawson has called for the UK to leave the European Union.

He said economic gains "would substantially outweigh the costs" and predicted Prime Minister David Cameron's attempts to renegotiate relations would be "inconsequential".

Leaving the EU would free the UK from red tape, he wrote in The Times.

Mr Cameron said his planned referendum would deliver "not just a voice... but a vote on our future in Europe".

The prime minister is facing increased calls to bring forward a promised referendum on the UK's EU membership following the success of the UK Independence Party in last week's local elections in England.

'Warm embrace'

He says he will hold a vote early in the next Parliament, should the Conservatives win the next general election, but only after renegotiating the terms of the UK's relationship with the EU.

However, Lord Lawson said any such renegotiations would be "inconsequential" as "any powers ceded by the member states to the EU are ceded irrevocably".

ANALYSIS Cabinet ministers took to the airwaves over the weekend to pledge that draft legislation would be introduced on an EU referendum before the next election. But if David Cameron thought that would appease those in the party who want to see a referendum sooner than 2017 he was wrong. Now, Lord Lawson, Margaret Thatcher's long-serving chancellor, has stepped up the pressure by calling for the prime minister to lead the country out of the EU altogether. His intervention is damaging for Mr Cameron. After losing support to UKIP in the local elections he wanted to get on the front foot over Europe. Instead the issue has again exposed deep divisions within his party over the issue that dogged the leaderships of John Major, William Hague and Iain Duncan Smith before him.

The peer - who was Margaret Thatcher's chancellor for six years - voted to stay in the European Common Market, the EU's predecessor, in 1975, but said: "I shall be voting 'out' in 2017."

He said he "strongly" suspected there would be a "positive economic advantage to the UK in leaving the single market".

Far from hitting business hard, it would instead be a wake-up call for those who had been too content in "the warm embrace of the European single market", adding: "Over the past decade, UK exports to the EU have risen in cash terms by some 40%. Over the same period, exports to the EU from those outside it have risen by 75%."

Withdrawing from the EU would also save the City of London from a "frenzy of regulatory activism", such as the financial transactions tax that Brussels is seeking to impose.

Lord Lawson said his argument had "nothing to do with being anti-European", adding: "The heart of the matter is that the very nature of the European Union, and of this country's relationship with it, has fundamentally changed after the coming into being of the European monetary union and the creation of the eurozone, of which - quite rightly - we are not a part.

"Not only do our interests increasingly differ from those of the eurozone members but, while never 'at the heart of Europe' (as our political leaders have from time to time foolishly claimed), we are now becoming increasingly marginalised as we are doomed to being consistently outvoted by the eurozone bloc."

'Clear timetable'

At the local elections last week, the UK Independence Party - which campaigns for the UK to leave the EU - made substantial gains, while the Conservatives lost control of 10 councils.

The UKIP surge prompted a call from some senior Tories bring forward the planned referendum, while some others have urged Mr Cameron to take steps to give the public more confidence that a referendum would indeed take place if he wins the next general election.

As it happens, those who run our biggest companies would tend to be horrified at the idea of withdrawal from the EU.

Asked whether Lord Lawson's comments had given UKIP a boost, Mr Cameron said: "I think it's been a good day for the pledge that, if re-elected, I will hold to it in a referendum, so that everyone can have not just a voice on everyone's future in Europe, but a vote on our future in Europe."

He added that he welcomed the attention Lord Lawson had brought to his plans to renegotiate the UK's relations with the EU.

Mr Cameron said: "I want to give people not just a choice between the status quo and leaving the EU, but the choice between staying in a reformed EU and leaving."

Deputy Prime Minister Nick Clegg said leaving altogether would "make us less safe because we co-operate in the European Union to go after criminal gangs that cross borders".

He said it could put three million jobs at risk, made it difficult to deal with cross-border threats such as climate change, and would also mean Britain was "taken less seriously in Washington, Beijing, Tokyo".

Replying, Lord Lawson told BBC Radio 4's World at One of the 3m jobs claim: "Well, that's poppycock - but I don't think Nick Clegg, who is a charming young man, has ever purported to know anything at all about economics."

UK Independence Party leader Nigel Farage said Lord Lawson's intervention "legitimised" his party's longstanding argument that the UK could prosper outside the EU, while exposing "serious divisions" in the Conservatives.

BBC political editor Robert Peston said the people running "our biggest companies would tend to be horrified at the idea of withdrawal from the EU".