NICOLA Sturgeon has said preventing Holyrood from holding an independence referendum before the UK leaves the European Union would be “democratically indefensible” if the move is backed by a majority of MSPs.

The First Minister stressed voters in Scotland must be given an alternative to Theresa May’s “hard Brexit”, which will take the UK out of both the EU and the single market. In last year’s referendum, 62 per cent of voters north of the Border supported remaining in the bloc and Sturgeon last week set out plans for a second vote on independence as a way of “protecting Scotland’s interests”.

Yesterday the Scottish Government published a parliamentary motion seeking backing to request the powers Holyrood needs to hold a plebiscite.

MSPs will debate the motion today and tomorrow, with the Unionist parties due to oppose it.Their stance prompted Scottish Green co-convener Patrick Harvie, who backs independence, to accuse them of trying to deny voters in Scotland a choice over their future.

The First Minster said last night: “The Scottish Parliament will be asked ... to support a motion to give the people of Scotland a choice over their future – once the terms of Brexit are clear, but before it is too late to change course.

“If MSPs pass this motion this week, then the Prime Minister’s position of blocking a referendum and forcing through a hard Brexit without giving the people a choice will be democratically indefensible.

“The sovereign right of the people of Scotland to determine the form of government best suited to their needs is a longstanding and widely accepted principle.

“Brexit will fundamentally change the form of government in Scotland – a change that Scotland opposed. The people of Scotland voted overwhelmingly to remain in the European Union, yet we now face being dragged out of Europe – and the single market – against our will.

“A hard Brexit threatens huge economic and social damage to Scotland, and the people must have the opportunity to choose a different, better path.”

She added: “Ultimately, this crucial decision over our future should not be made unilaterally by me, or by the Prime Minister – it should be made by the people of Scotland, and I call on Parliament to give the people that choice.”

The motion, put forward by the First Minister, asks the Scottish Parliament to acknowledge “the sovereign right of the Scottish people to determine the form of government best suited to their needs”, and “mandate the Scottish Government to take forward discussions with the UK Government” on the details of a Section 30 order.

The details of the order should ensure that Holyrood can legislate for a vote “at a time, and with a question and franchise, determined by the Scottish Parliament, which would most appropriately be between the autumn of next year ... and around the point at which the UK leaves the EU in spring 2019”, the motion adds.

The support of the six Scottish Green MSPs means the motion is expected to be passed tomorrow despite the SNP not having a majority in Holyrood.

Harvie’s party has lodged an amendment to the Scottish Government motion calling for the referendum to have a franchise which would includes votes for 16- and 17-year-olds, and for EU citizens.

Their amendment also adds a referendum is necessary given the UK Government’s decision to negotiate a "hard" exit from the EU and its failure to take account of the strong Remain vote in Scotland.

Harvie said: “The people of Scotland deserve to have a choice, and it’s appalling to see anti-democratic Tories trying to close down our options, while a feeble Labour party simply rolls over on what will be a devastating hard Brexit we did not vote for.”

Despite polls indicating around 50 per cent of Scots want a referendum within two years – the timescale for the vote set out by the First Minister – the Tories insist there is no “public or political consent” for a referendum.

Scottish Labour leader Kezia Dugdale added: “The party I lead will never support independence.”

Meanwhile, Number 10 has insisted there is not going to be an early election. Reports yesterday suggested Tory chairman Patrick McLoughlin and Chief Whip Gavin Williamson had been encouraging May to go the country on May 4 in a bid to increase the government’s small majority.

However, the Prime Minister’s official spokesman yesterday told reporters that an early General Election was “not going to happen.”