NICOLA Sturgeon will need Westminster co-operation to hold a second independence referendum, ministers have confirmed.

A draft referendum bill, published this morning, show that a Section 30 order temporarily transferring legal powers to Holyrood would be sought if the legislation is introduced at the Scottish Parliament.

In a pre-amble to a consultation accompanying the draft bill, the Scottish Government states that it would be "expected" that a Section 30 order would be granted, as it was ahead of the 2014 vote.

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Nicola Sturgeon has said previously that it is "inconceivable" that Theresa May would block a vote. However, other SNP figures including former justice secretary Kenny MacAskill have said it is "perfectly feasible" that Number 10 will refuse to grant the powers. The UK Government has not yet given a definitive answer to the question.

It is proposed at this stage that the same question as in 2014, 'should Scotland be an independent country?' would be used in a second referendum although a variation has not been ruled out following the consultation. Scotland's constitutional future would be decided by a simple majority, with no minimum turnout threshold.

As in 2014, 16 and 17-year-olds would be eligible to vote, as would EU citizens. Minor changes to 2014 are proposed around absent voting arrangements, permitted participants and appointment of polling and count staff.

The consultation asks about technical aspects of the bill, not whether a repeat referendum should be held.

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Ms Sturgeon has said she will move for a second referendum if she concludes independence is the best or only way to protect Scotland's interests, following the UK's decision to quit the EU.

In June, 62 per cent of voters opted to remain, in contrast to 52 per cent who backed Brexit UK-wide.

The First Minister, in the foreword to the consultation document, said that the SNP has been elected on a "clear mandate" that Holyrood should have the right to hold a referendum, if there was a "significant and material change in circumstances" to 2014 such as Scotland being taken out of the EU against its will.

She added: "Scotland is now faced with one of the specific scenarios in which this government pledged that the Scottish Parliament should have the right to hold an independence referendum.

"The UK Government’s recent statements on its approach to leaving the EU raise serious concerns for the Scottish Government. We face unacceptable risks to our democratic, economic and social interests and to the right of the Scottish Parliament to have its say.

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"Indeed those statements contradict the assurances given before the independence referendum in 2014 that Scotland is an equal partner within the UK and that a vote against independence would secure our EU membership.

"For many people, this approach will be evidence of a wider democratic deficit within the UK, where decisions about Scotland are too often taken against the wishes of people who live here."

She added: "This government remains willing to work with the UK Government to negotiate a future relationship with Europe that is in line with the views of the overwhelming majority of the Scottish people and which works for the United Kingdom as a whole.

"We will put forward constructive proposals that will both protect Scotland’s interests and give an opportunity for the UK Government to demonstrate that Scotland is indeed an equal partner.

"But if it becomes clear that it is only through independence that Scotland’s interests can be protected, then the people of Scotland must have the ability to reconsider that question, and to do so before the UK leaves the EU."

Constitution Minister Derek Mackay holds a copy of the Draft Referendum Bill published by the Scottish Government at St Andrews House in Edinburgh. Photo: PA

Launching the document, Scottish Constitution Secretary Derek MacKay said: "It's inconceivable that the Tory Government would not grant a section 30 order. They need to respect Scotland, and the Prime Minister said she would do that.

"This consultation shows how we're taking the good working arrangements from 2014. So the UK Government recognised a mandate in 2014 and we have a mandate in 2016.

"There are not circumstances of our making, it is the making of a right-wing UK Tory Government, so it's inconceivable that they would try and block Scotland having its say in the circumstances."

On a possible timetable for a second referendum, he added: "The UK Government said that Brexit, in terms of triggering Article 50, could be a two-year process. Legislation in the Scottish Parliament could take between six and nine months.

"This is a 12-week consultation so it is feasible and plausible to have a Scottish independence referendum within that two-year period."

The minority SNP Government could get legislation for a second independence referendum through the Scottish Parliament with the support of the pro-independence Scottish Greens, while all other parties at Holyrood oppose another vote on the issue.

Welcoming the draft Bill, the Greens' co-convener Patrick Harvie said: "The Westminster Government's inability to acknowledge the overwhelming mandate for Remain in Scotland, or demonstrate any kind of flexibility the union could take in the individual UK nations' forging relations with Europe, shows that independence is quickly becoming the most realistic option for Scotland to shape its own partnership with the European Union.

"Every opportunity must be explored to keeping Scotland in the European Union and that now includes the option of an independence referendum.

"It would be foolish for the UK Government to stand in Scotland's way, having already disregarded the 62% who voted to Remain earlier this year."

Scottish Conservative leader Ruth Davidson said: "During her Programme for Government, the First Minister made great play of how she had a number of priorities ahead of independence.

"The SNP even criticised other parties for making reference to the issue during the debate. Yet today we see that once again it is the SNP's top priority.

"This is the first major Bill Nicola Sturgeon has published after being re-elected as First Minister and shows that separation is her overriding concern."

Describing the draft Bill as "irresponsible economic vandalism", Scottish Labour leader Kezia Dugdale said: "Our economy is in trouble following David Cameron's reckless Brexit gamble, and the very last thing we need is more uncertainty for employers.

"This publication confirms that the SNP's top priority is to divide our country. My message to the First Minister is this: we are divided enough - do not divide us again.

"Instead of seeking fresh divisions, the SNP should be prioritising our public services such as education and healthcare.

"This is a referendum that Scotland does not need or want."

Scottish Liberal Democrat leader Willie Rennie said: "Just two short years after we voted decisively to remain part of the United Kingdom, the SNP are dragging Scotland back to division over the constitution.

"Scotland has not had a mental health strategy since the end of last year but the SNP managed to turn around a referendum Bill in weeks.

"It is now crystal clear that the SNP's priority is not education. It is not health, or even working to protect the benefits of our EU membership. It is independence."

Scottish Secretary David Mundell said: "The issue of whether Scotland should leave the UK was settled conclusively in 2014. The people of Scotland said no decisively then and there is no public attitude for a second referendum now.

"People in Scotland need a Scottish Government that is focused on the day job - not obsessed with pushing their ideological agenda at any cost.

"The UK is the vital union for Scotland and my clear priority is to get the best possible deal as we leave the EU. To do that we need to take this distracting and divisive issue of independence off the table."