DAVID Cameron has claimed independence would pose a bigger threat to Scotland's membership of the EU than his own plan for a vote on Britain's future in Europe.

The Prime Minister said a Yes vote in next month's referendum would "automatically" remove Scotland from the EU, leaving the newly independent state with no guarantees over the terms of membership when it eventually joined.

He spoke out following criticism from business leaders of his plan to hold a referendum on the UK's EU membership in 2017, if he wins a majority at the next election.

In an embarrassing dressing down, the president of the CBI, Sir Mike Rake, said the policy was damaging business in speech to members in Glasgow attended by Mr Cameron.

But speaking during a visit to an engineering firm in Midlothian, Mr Cameron said: "If Scotland votes for separation it leaves the European Union automatically. It then has to join the queue to get back into the EU, and there can be no guarantee that that will be a swift or easy process.

"If Scotland votes to stay inside the UK, we're members of EU."

Defending his own policy, he added: "I've promised a referendum on that membership before the end of 2017 and that is a position that is supported by a majority of people in Scotland, who think it is right to renegotiate to get a better relationship with Europe and then have a referendum.

"It's not just supported by a majority of Scots, it's also supported by a majority of Alex Salmond's own party, so I'm not surprised he's in a bit of a muddle about this issue." Mr Cameron has said he wants to campaign for Britain staying in the EU.

Sir Mike Rake's comments were seized on by the SNP, which has argued that Mr Cameron, not independence, poses the "real threat" to Scotland's continued membership of the Brussels club.

In a BBC radio interview yesterday, First Minister Alex Salmond insisted Mr Cameron's policy was "ridiculous". He added: "The politics of Euroscepticism that we see in Westminster are deeply damaging for Scotland, and could be even more damaging if we are dragged out of Europe."

Mr Cameron also admitted the Conservatives were unlikely to win many seats in Scotland at the next Westminster election. He said: "I know that despite how hard I work in Scotland, I probably won't have a huge number of Scottish seats."