EU exit would be 'fatal mistake' says Ken Clarke
Leaving the European Union would be a "fatal mistake" for the UK, former chancellor Ken Clarke has said.
In a speech, the minister without portfolio said the case for Britain's membership and its benefits must be made "more strongly and coherently".
He later told BBC Radio 4 it was inconceivable that PM David Cameron would campaign for a No vote.
Conservative Eurosceptics say Mr Clarke is out of step with the party and the public on the need for a referendum.
Mr Cameron has pledged to renegotiate the UK's membership and put the "better deal" he hopes to secure to a vote of the British people before the end of 2017.
The pledge has been warmly welcomed by most Conservative MPs who believe that Brussels has accrued too much power and that decision-making in many areas should return to Westminster.
But Mr Clarke, one of the party's most pro-European voices, warned his colleagues that they needed to "concentrate on what we are in favour of and not just what we are against".
Speaking at the launch of a new cross-party lobby group which aims to promote the benefits of British membership, Mr Clarke acknowledged that the EU's institutions needed reform and that David Cameron had made a "strong case" for areas where the union could be working better.
But he said the UK should focus on three areas - completion of the single market, enlargement of the EU and trade deals with the US and other leading economies - where progress could not be achieved alone and which would make both the UK and the EU a "more effective global power".
"There is a huge potential prize out there for the UK if only we focus our attention and influence in any future negotiations on the positive things that really matter," he said.
Although Mr Clarke did not refer directly to the Conservative leader's referendum pledge, he warned that it was in the UK's "vital national interest that we avoid the fatal mistake that would be a No vote if a referendum is held in the next few years".
He suggested that the case for British membership of the EU had not been "made properly for many years" and the "time has obviously come" for the arguments to be set out.
In an interview with BBC Radio 4's Today programme, Mr Clarke later explained that the government had concluded that a referendum was "the only way of resolving what is otherwise a long-running, noisy debate".
But he also argued that referendums were "not as good as parliamentary democracy".
"When Parliament votes, all the members have continuing responsibility for the consequences of their votes and how things work out afterwards, and you can throw them out if the consequences start going wrong," he said.
"But I'm, as it were, resigned to fate, that is to becoming a minority view in today's more activist world."
Questioned on whether Mr Cameron would campaign for a No vote if the government were unsuccessful in its planned re-negotiation, he added: "I don't think he could conceivably start urging people to vote No, after all he's said about his reasons for being members of the EU.
"The whole policy is designed to stop this permanent, sort-of battle about why we're in Europe, and to improve our relationship with Europe and Europe itself."
BBC political correspondent Iain Watson said Mr Clarke's speech was not surprising but represented "coded criticism" of the prime minister's strategy.
Speaking with Mr Clarke at the lobby group's launch, senior Lib Dem MP Danny Alexander said the UK could not afford to give the impression that it was "going to disengage" from the EU in any way.
"The idea that we should extract ourselves from the bulk of EU obligations is nonsensical," the chief secretary to the Treasury said.
Earlier in the House of Commons, Conservative MP John Redwood - who served alongside Mr Clarke in John Major's Cabinet - suggested that the UK had been reduced to an "e-mail democracy" by Brussels.
"We receive the emails or the faxes from Brussels and this Parliament has to put through the measure whether we like it or not," he told MPs during a debate on Europe.
Praising Mr Cameron's rejection of "ever-closer union" - one of the EU's founding principles - he said the UK simply did not share the aims of many other EU members.
"We should all join together now in rallying the peoples of Europe to say yes to friendship, yes to trade, yes to co-operation but no to centralisation and no to authoritarian interference."
And Labour MP Kate Hoey, one of the party's leading Eurosceptics, said Mr Cameron had been "absolutely right" to offer the public their say over the issue and she expected Labour to follow suit in due course.
"Before the European elections, without doubt, my party will be saying we want to have a referendum because it is a basic tenet of democracy."