Business chiefs have a duty to speak up for Britain's membership of the EU, says Douglas Alexander

The Shadow Foreign Secretary, in a speech to ambassadors from all 28 EU member states, claimed the Conservative Party's approach to Europe posed "the biggest risk to British national prosperity in a generation", with David Cameron putting Britain "on the conveyor belt to exit" from the EU despite being aware that it represented "a remarkably irresponsible gamble".

The Paisley MP said pro-EU business leaders should learn the lessons of the Scottish independence referendum, when many companies delayed expressing a view until the last minute but were then seen as playing a crucial role in shaping the final days of the campaign.

??Jolted into action when a YouGov poll just weeks before the referendum seemed to show that the Scottish public would vote to leave the Union, businesses began to speak up about the risks this could bring...When they voiced genuine concerns about the impact of policies on jobs and investment, people across Scotland listened.??

Mr Alexander stressed how he understood why Scotland??s business leaders were reluctant to speak out for fear of becoming ??political targets??.

But making clear the example of the Scottish referendum should be learned from, he went on: ??Once again, business faces the dilemma of how to face down a populist leader mobilising and an increasingly angry public campaign.

??Last summer, it was about Scotland leaving the UK. Next summer, it could be about the UK leaving Europe.??

Using a similar line his colleague Ed Balls used at the weekend about what future Tory proposals would mean for public services, the Shadow Secretary of State said the election of a Conservative government next year would mean ??breaking with decades of history that have defined the country we are today, how our country is run, and the place we have in the world".

Mr Alexander, who stressed Labour??s plan was not exit from Europe but reform within it, suggested victory for David Cameron in 2015 would mean ??we could be out of Europe and dealing with a full-blown constitutional crisis across the United Kingdom??.

The SNP leadership has already suggested any EU vote would need a double majority ?? across the UK and within Scotland ?? for the decision to stand; the clear suggestion is that if Scots voted to stay within the EU but the UK voted the other way, then there would be a second independence referendum.

Meantime, Katja Hall, the CBI Deputy Director-General, made clear most of the body??s members believed the UK was best placed to create jobs and growth as part of a reformed EU.

"While the EU isn't perfect, the UK does have influence as a full member and no other alternative offers to British firms what membership of the EU can like access to a market of 500m people and signing major trade deals," she said.

Matthew Elliott, Chief Executive of Business for Britain, said: "Independent polling shows that 66 per cent of businesses back a referendum as they know it's the only way to secure a better deal from the EU.

"Try telling Scotland you don't get a better deal if people think you are serious about the alternative to membership of a union. Perhaps instead of asking businesses to speak up, Mr Alexander should start listening to them?" he added.

Last night, No 10 insisted the Prime Minister believed it was in the UK??s national interest to stay within the EU but a reformed EU.

"Part of that reform is about a more economically competitive European Union and that's a view that is widely shared by businesses up and down the country, including, for example, those who are on the Prime Minister's EU Business Task Force."