Voters across the UK are more worried about the prospect of Scottish independence than Brexit, according to a new poll.

The findings suggest that fears over the possible break-up of the Union could help keep the UK in the European Union (EU).

David Cameron is among those who have warned voters south of the border to think of Scotland before they cast their ballot on June 23.

But the poll also found that, if pushed, more than half of those of those who oppose Brexit think the UK’s EU membership is more important than Scotland remaining in the Union.

The findings came as Nicola Sturgeon faced more questions over a second independence referendum.

Campaigning in Edinburgh, the First Minister insisted that her position was "rooted in democracy".

She has accused Labour, the Conservatives and Liberal Democrats of being "frightened" of facing a second vote.

But the leaders of the three main pro-Union parties have called on her to respect the outcome of the last referendum.

The SNP leader has said that another vote could be triggered if Scotland is taken out of the EU against the will of Scots.

Polls suggest that while most Scots back remaining in the EU, the picture in England, where 85 per cent of the UK population lives, is more mixed.

The BMG poll for The Herald poll found that voters south of the border were twice as concerned about Scottish independence as they wer about leaving the EU.

Those who want to remain in the EU were strongly against Scottish independence, by 72 per cent to 28 per cent.

When asked to choose, however. 56 per cent said that their "least preferred" option was Brexit, while a smaller number, 44 per cent, said Scottish independence.

The poll also found that around four in 10, 42 per cent, of those who want to leave the EU think Scotland should be independent.

Among undecided EU voters most, 71 per cent, were against Scottish independence, and a similar proportion, 73 per cent, thought independence would be a worse outcome than Brexit .

The poll also found that younger people were less likely to be concerned by Scottish independence than Brexit than older people.

Experts said that the findings suggested that young people values had moved more towards the continent than those of their parents or grandparents.

A Scottish Liberal Democrat spokesman said that the SNP would “do well to remember” that debate over the EU referendum “is not a proxy one for Scottish independence”.

"Liberal Democrats stand firmly for Scotland remaining part of the UK and the UK remaining part of the EU,” he added.

The Scottish Conservatives said: that people “right across the UK were concerned about the prospect of Scotland being independent. That was shown in a number of rallies, and a recognition that the UK needed Scotland as much as Scotland needed the UK.”

A Scottish Labour spokesman said: “The best future for Scottish jobs and Scottish families is to stay in the UK and the EU. Scottish Labour is fully committed to the UK remaining in the European Union.”

An SNP spokesman said: ''Only the people of Scotland can and will determine this country's constitutional future. But, as we have made clear, the prospect of Scotland being dragged out of Europe against our will would almost certainly spark strong demands for a second independence referendum."

Labour leader Kezia Dugdale yesterday accused both the SNP and the Conservatives of being “utterly obsessed with re-running the constitutional arguments of the past”.

At the weekend Ms Sturgeon said that she expected to lead Scotland to independence in an interview with The Herald's sister paper, the Sunday Herald.

Yesterday (MON) she told BBC Radio 4's Today programme that opinion polls could trigger another independence referendum.

She said that there would have to be "clear and sustained evidence... over a period of time, that independence had become the preferred option of the majority."

Speaking on the campaign trail, Ms Sturgeon said: "My position on a second referendum is rooted in democracy - if there is no demand for it there won't be one, on the other hand if people want independence, if it becomes the preferred option of a majority, then I don't think anyone has the right to stand in its way.

"Thursday's election though is not a vote for Scotland to become independent, it is a vote for a programme of government put forward by the SNP."

Scottish Liberal Democrat leader Willie Rennie has accused her of being "anti-democratic" on the issue, while Scottish Conservative leader Ruth Davidson accused the First MInister of "keeping this wound open".