FIRST Minister Nicola Sturgeon is under mounting pressure to back a referendum on Brexit after a new opinion poll found overwhelming support for the idea from SNP members.

As her party prepares for its conference in Glasgow today, a YouGov poll showed 89% of respondents backing a new vote and 79% saying that SNP MPs should back the policy in the House of Commons.

A spokesperson for the People’s Vote campaign, a group calling for another referendum, said:

“Regardless of Scotland’s constitutional future – and the People’s Vote campaign has no view one way or another on that important question – a People’s Vote offers us all a chance to keep Scotland, and the rest of the UK, in the EU now.

“As the vast majority of people in Scotland know, that is vital for jobs, investment, public services, citizens’ and workers’ rights and environmental protection.”

Although a staunch critic of Brexit, Ms Sturgeon has offered tentative and conditional support for a referendum on the UK Government's final deal with the European Union.

Ms Sturgeon has said she could back another vote, but not if voters in Scotland were ignored, as she believes they were in the 2016 plebiscite.

Party figures are also nervous that a two-stage referendum process could create a precedent if Scotland voted for independence.

However, some of her allies, including former special adviser Noel Dolan, have called on the First Minister to unequivocally back another vote.

According to the YouGov poll, which was commissioned by the People’s Vote, SNP members are attracted to the prospect of stopping Brexit through another referendum.

The sample of over 650 SNP members found that 93% - once “don’t knows” are excluded - would vote to stay in the EU if they were given a chance.

Around 83% said they would support another vote, but this figure jumped to 89% once the “don’t knows” were taken out of the calculation.

SNP MPs could also face grassroots pressure, as 79% of polled members said their Westminster parliamentarians should back a vote if it came up at Westminster.

Barely 8% of those polled wanted their MPs to oppose the measure and 13% said party MPs should abstain.

The YouGov poll also showed that 84% of party members want SNP MPs to oppose any Brexit proposal brought forward by the UK Government.

Peter Kellner, a pollster and past president of YouGov, said:

“The results could scarcely be more emphatic. Ahead of the SNP’s conference, its members say their MPs should support an amendment to the Withdrawal Bill ‘to make sure there is a new public vote on Brexit before the UK leaves the EU’. There had been some talk of SNP MPs abstaining on this issue; but this option is backed by only 13% of party members.

Scottish Liberal Democrat leader Willie Rennie said:

“Nicola Sturgeon and her ministers have exhausted their excuse selection. Now that it’s clear the vast majority of SNP members want to have the final say on Brexit they can’t justify sitting on the fence any longer. Brexit poses a huge threat to people’s livelihoods, security and public services.

“I have relentlessly called on the First Minister to step up and join the cross-party fight against this imminent economic disaster. Hopefully the dismay of her own members will make her see sense.”

Stephen Gethins MP, the SNP’s Foreign Affairs and Europe spokesperson, said:

“This polls reveals that SNP members see straight through the Tories false claims on Brexit, and hold absolutely no faith in the Tory government being able to deliver.

“The SNP would not block a People’s Vote if there is support for it across the rest of the UK. However, in 2016 Scotland voted overwhelmingly to remain within the EU, but now finds itself in the position of being dragged out against its will. Those advocating for a People’s Vote must be clear that Remain will be an option on any ballot, and that it should set out clearly how Scotland will be protected if it once again votes to remain, whilst the rest of the UK votes to leave.”