THE SNP has seized on reports that David Cameron is planning to raise the spectre of Britain leaving the European Union if it does not get radical reforms as proof that only a vote for independence would keep Scotland within it.

It has been suggested that informed sources claimed Downing Street could turn up the heat by opening up the possibility of Britain's EU exit during next month's Tory conference.

It is believed some in No 10 considered issuing the threat in July after Jean-Claude Juncker was made European Commission President despite the UK's opposition. A source was quoted as saying: "The shift was almost made public at the time Juncker was appointed but that timing might have looked like petulance."

The PM's aides remain confident significant powers will be returned to Britain, enabling Mr Cameron to campaign to stay in a reformed EU during his proposed in/out referendum in 2017.

But yesterday the Nationalists stressed how the reports made clear the Conservative leader was preparing to change his position on Britain's membership of the EU unless Brussels agreed to his terms for reform.

"Membership of the European Union is good for Scotland economically, politically and culturally; the fact that we could find ourselves ripped out of Europe against our will by a Euro-hostile UK Government Scotland didn't vote for highlights exactly why we need a Yes vote," said SNP MSP Christian Allard.

He warned a UK departure from the EU would have a devastating impact on business. "The idea David Cameron is willing to risk these consequences just to appease Ukip and his more extreme backbenchers speaks volumes about the priorities of the Westminster Establishment."

He argued people in Scotland completely rejected the "anti-Europe agenda of Westminster".

"While Westminster retreats inward, people in Scotland want to engage positively with the international community.

"A Yes vote next month is our one opportunity to give Scotland a voice at the top table and to be a positive, constructive member of the EU; in stark contrast to isolation and irrelevance with a Westminster Establishment that is dancing to Ukip's tune."