THE fight for Scotland to be a sovereign nation has been renewed after more senior Labour figures shifted their stance and the party began exploring the option of a federal UK.

After a poll published yesterday was the third since Thursday’s Brexit vote to indicate a majority of voters north of the Border were now in favour of a Yes vote in the event of indyref2, interventions from Ian Murray and Margaret Curran suggested the party could be on course to review its long-established opposition to independence.

Meanwhile, senior figures in Scottish Labour were reported to be investigating proposals for Scotland and Northern Ireland to have separate federated membership of the EU. Party sources told The Guardian the former Labour Lord Chancellor and Justice Secretary Charlie Falconer was consulting constitutional lawyers on whether a new federal relationship would be a legally sound alternative route to a full divorce between the EU and all parts of the UK.

Murray, who resigned from Jeremy Corbyn’s shadow cabinet at the weekend, said all options were being explored to protect Scotland’s EU membership – including support for another independence referendum.

The former Shadow Scottish Secretary told BBC Radio Scotland’s Good Morning Scotland programme: “Kezia Dugdale has made clear that our manifesto said that we would oppose a second independence referendum.

“We’re a party that believes in Scotland being both in the UK and in the EU, but she has said that nothing is off the table at the moment until we see where we are and what will be.”

Writing in The Times yesterday, Curran, Shadow Scottish Secretary while the party was leading the Better Together campaign ahead of the 2014 referendum, said: “The EU referendum revealed an increasing divergence between the politics of Scotland and the rest of the UK. There are those who will say the response is independence.

"Having campaigned against independence, it breaks my heart that we are here again. And we must be honest: the case for independence in 2018 could be stronger than in 2014.”

However, she also indicated she was still reluctant to back independence personally. “While I understand the politics is shifting, I am compelled to acknowledge the values that drove me to support staying in the European Union are those that drive me to support a continuing partnership across the UK,” she said.

However, she conceded that “Scottish Labour must face square on the growing divergence between the politics of Scotland and the rest of Britain”. She added: “Scottish Labour must serve Scottish voters first. Kez has been right to say she will work in tandem with the First Minister in the best interests of Scotland and get the best deal possible. She must be unafraid if that puts her at odds with other parts of the Labour movement.”

A Survation poll of 1002 adults published in the Labour-supporting Daily Record, carried out after the Brexit vote, found 54 per cent would back independence, against 46 per cent who would not.

Today the First Minister will seek a mandate from Holyrood to keep Scotland in the EU once talks take place with European Union leaders.

Ahead of the parliamentary debate she told journalists she would not be seeking to persuade Scottish Labour to back independence, but would do so if a second independence referendum was called.

Scottish Secretary David Mundell yesterday accused Sturgeon of “opportunism” to further the “independence agenda”. He insisted the arguments for Scotland being part of the UK were “as compelling today as they were in 2014”.

Responding to the Survation poll, SNP business convener Derek MacKay said: “This poll is a strong endorsement of the actions of the First Minister and shows that when faced with the choice between being taken out of the EU against our will by a right-wing Tory government, or continuing as outward-looking, independent members of the European Union, more and more people are open to the possibilities independence brings.”

Responding to suggestions the First Minister may ask MSPs to block EU withdrawal legislation, David Cameron’s spokeswoman yesterday said there was no requirement for Holyrood to approve it. She was also asked whether the PM would oppose a second Scottish independence referendum, and said: “The PM’s view has not changed. There was a legal, fair and decisive referendum nearly two years ago.”