Brexit has split the Scottish Nationalists and Eurosceptic voters have fled the SNP for the Tories, according to a detailed analysis published ahead of the party's conference starting on Friday.

Sir John Curtice, Britain's most eminent psephologist, and Ian Montague found "a new divide" has been created in the nationalist movement over their attitudes to leaving Europe.

In a report for the National Centre for Social Research (NCSR), they said Nicola Sturgeon's pro-EU stance had cost her party votes and seats in last year's snap general election.

Support among Eurosceptics for the SNP dropped from 51 per cent in the 2015 election to only 36 per cent in last year's contest, when it lost 21 MPs including Alex Salmond and Angus Robertson.

Eurosceptic backing for the Tories increased by 14 points between the two elections, to 28 per cent, compared to a four-point rise among EU supporters.

The survey of 1,234 Scots also found that nearly six out of 10 (58 per cent) describe themselves as Eurosceptic compared to only 37 per cent who say they are Europhiles.

But support for independence has held steady at 45 per cent, the same level recorded in the 2014 referendum, and there has been a marked increase from 26 per cent to 41 per cent in the proportion of Scots who think separation would improve the economy.