SCOTTISH independence will become “increasingly irresistible” if Scotland is taken out of the European single market, according to the SNP.

Nicola Sturgeon stepped up her efforts to keep Scotland in the single market, amid reports that Theresa May is about to sign off on a special deal for Northern Ireland.

The First Minister retweeted a new Survation poll suggesting 47 per cent of Scots now favour breaking away from Britain, slightly higher than the 45 per cent that voted for independence in 2014.

She said: “If one part of UK can retain regulatory alignment with EU and effectively stay in the single market (which is the right solution for Northern Ireland) there is surely no good practical reason why others can’t.”

She added: “Right now, Ireland is powerfully demonstrating the importance of being independent when it comes to defending your vital national interests.

Nicola Sturgeon made the comments as Britain and the EU appear to be moving closer to agreement on key issues, including the status of the Irish border.

Arrangements which would effectively allow Northern Ireland to remain part of the European single market would prevent the return of a "hard border" between the North and the Republic of Ireland.

However, anything that ties Northern Ireland too closely to the Republic risks alienating Theresa May's allies in Ireland's Democratic Unionist Party (DUP), whose votes she needs to get the Brexit Bill through parliament.

DUP Leader Arlene Foster said: "Northern Ireland must leave the EU on the same terms as the rest of the United Kingdom. We will not accept any form of regulatory divergence which separates Northern Ireland economically or politically from the rest of the United Kingdom. The economic and constitutional integrity of the United Kingdom will not be compromised in any way."

Scotland, Northern Ireland and London voted to remain part of the EU in the referendum which was held in June 2016.

Sadiq Khan, the London Mayor, also demanded a special deal for the capital if Northern Ireland is allowed to effectively stay in the single market.

“Huge ramifications for London if Theresa May has conceded that it's possible for part of the UK to remain within the single market and customs union after Brexit,” he said.

“Londoners overwhelmingly voted to remain in the EU and a similar deal here could protect tens of thousands of jobs.”

Wales voted to Leave the EU, but Welsh First Minister Carwyn Jones has also joined the clamour for special deals following reports of breakthrough in Ireland.

“We cannot allow different parts of the UK to be more favourably treated than others,” he said.

“If one part of the UK is granted continued participation in the single market and customs union, then we fully expect to be made the same offer.”

Derek Mackay, the SNP business convener, said: “Too many decisions which determine our fate are still made at Westminster, including the hard line approach to Brexit that would see Scotland dragged out of the single market at a huge cost to jobs and our economy.

“As people realise how damaging that will be, independence becomes an increasingly irresistible alternative and this poll points to a clear movement in that direction.”

The SNP will table a series of amendments in the Commons today to try to prevent “the biggest power grab Scotland’s Parliament has faced since being reconvened in 1999”.

However, Scotland’s Brexit Minister Michael Russell yesterday warned the Scottish Government might still reject the Brexit Bill even if Westminster bows to its demands for more powers.

He said there are other elements of the Bill that the SNP “thoroughly dislike” beyond the proposal to transfer all the EU’s current powers to London rather than hand them to the devolved nations.

Henry McLeish, the former Labour first minister, today urged unionists to embrace a federal United Kingdom to head off the threat of independence.

“Federalism is all about ‘effective’ power,” he said.

“Rejection by Unionists will inevitably lead to an independent Scotland, time line unknown."