David Cameron will attempt to capture the Olympic spirit of “Team GB” today in an effort to rally opposition across the United Kingdom to Scottish independence.

Following signs that support for separation is growing north of the border, he will warn against complacency over the result of the referendum vote, insisting its outcome is “still up in the air”.

The Prime Minister will deliver his patriotic appeal at the site of the 2012 London Olympics, which he will argue symbolises the combined strength of the four parts of the UK pulling together.

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“For me, the best thing about the Olympics wasn’t the winning. It was the red, the white, the blue,” he will say.

“It was the summer patriotism came out of the shadows and into the sun, everyone cheering as one for Team GB. And it is Team GB I want to talk about today, our United Kingdom.”

Polls suggest that around 40 per cent of Scottish voters remain firm in their opposition to breaking away, but that Alex Salmond, the Scottish First Minister, is building momentum for a yes vote.

Support for separation has edged upwards since the Holyrood government published its white paper on independence in November and is now close to 30 per cent.

The Better Together team has also faced some criticism for running a lacklustre campaign compared with the Nationalists.

Mr Cameron will seek to ignite a UK-wide by arguing that everyone would be affected if Scots voted on 18 September to break up the Union.

“Although only four million people can vote in this referendum, all 63 million of us are profoundly affected. There are 63 million of us who could wake up on 19 September in a different country, with a different future ahead of it,” he will say at the Olympic Park.

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“We would be deeply diminished without Scotland. This matters to all our futures and everyone in the UK can have a voice in this debate.”

He will argue: “If we lost Scotland, if the UK changed, we would rip the rug from under our own reputation. The plain fact is we matter more in the world together.

“There can be no complacency about the result of this referendum. The outcome is still up in the air and we have just seven months to go, seven months to do all we can to keep our United Kingdom as one, seven months to save the most extraordinary country in history, and we must do whatever it takes.

“So to everyone in England, Wales and Northern Ireland – everyone, like me, who cares about the United Kingdom – I want to say this: you don’t have a vote, but you do have a voice.

“Those voting are our friends, neighbours and family, you do have an influence.”

Last night Scotland’s Deputy First Minister, Nicola Sturgeon, accused Mr Cameron of a “shameful” bid to use the Olympics as a “political tool” as the 2014 Winter Games begin in Russia. She claimed his “cowardly” intervention was evidence of jitters in the No camp.