NICOLA Sturgeon has published controversial legislation paving the way for a second independence referendum despite lacking the critical power to hold one.

The First Minister said the 168-page Referendums (Scotland) Bill could see the country choose to be an independent European nation, rather have Brexit imposed on it.

READ MORE: Why it’s time for an advisory referendum on independence 

The Bill would set the rules for any referendum within Holyrood’s current competence.

But it is also intended to serve as the basis for an independence referendum - a step that would require the transfer of extra power from Westminster under a Section 30 order.

Without such a power, the referendum would be open to legal challenge and stall in court.

Ms Sturgeon has said she wants to hold Indyref2 in the second half of next year.

However, as Theresa May has already refused to grant a Section 30 order, and her successors seem equally unlikely to oblige, the Bill seems largely for show.

Knowing it will be denied the power to bring it to life, Ms Sturgeon will be able to cite the refusal as further evidence of Westminster ignoring Holyrood at the 2021 election.

Ms Sturgeon said today it would be a "democratic outrage" if the UK Government blocked Indyref2. 

SNP Brexit Secretary Michael Russell failed to identify any other issues the Bill could be used for when questioned by MSPs in the Holyrood chamber.

The Scottish Tories claimed the legislation was a “Trojan horse” for Ms Sturgeon to call a Catalan-style wildcat referendum without Westminster’s consent.

However the First Minister recently explicitly ruled out any such referendum.

The SNP government said it expects the Bill to become law by the end of this year, a passage that will require the support of the Scottish Greens.

Labour, the Tories and LibDems all oppose the Bill and say it is a time-wasting distraction from more pressing issues such as health and education.

Presiding Officer Ken Macintosh said the Bill was within Holyrood’s legislative competence.

READ MORE: Politics Live: Scottish independence legislation to be tabled at Holyrood 

Ms Sturgeon said: “Now, more than ever, it is essential that we keep Scotland’s options open so that people have the opportunity to choose a better future.

“An independence referendum within this parliamentary term will give Scotland the opportunity to choose to be an independent European nation - rather than have a Brexit future imposed upon us.

“Throughout the Brexit process, Scotland has been treated with contempt by Westminster, and our efforts to find a compromise and protect the interests of the people of Scotland, who voted overwhelmingly to remain in the EU, have been ignored.

“We will seek agreement to a transfer of power at an appropriate point to enable an independence referendum that is beyond challenge to be held later in this parliament.

“It is essential the UK Government recognises that it would be a democratic outrage if it seeks to block such a referendum - indeed, any such stance would, in my view, prove to be utterly unsustainable.”

Before the 2014 independence referendum, the UK and Scottish governments agreed the temporary devolution of referendum powers before legislation for a referendum.

This time, the process has been reversed, with the legislation being processed first in the hope that a Section 30 order is granted in future.

Constitutional Relations Secretary Michael Russell said: “Although referendums have become an increasingly common feature of UK democracy, it is a long time since the framework governing them was last comprehensively reviewed.

“Introducing a standing framework for referendums is a reasonable thing for any country or Parliament to have and this legislation will put Scotland in the same position as the UK and many other countries.”

Scottish Conservative constitution spokesman Adam Tomkins said: "In reality, this is Nicola Sturgeon laying the ground for a ‘wildcat’ second referendum on independence.

“The tabling of this legislation is merely another opportunity to allow the First Minister to talk about her pet obsession with the break-up of Britain.

“Under this Bill, SNP ministers would have the power to set any referendum question, at any time, on any matter of their choosing. It’s a power grab on an industrial scale.

“It would be nationalist ministers – not the Scottish Parliament – who would set the question, pick the date, and determine the campaign period.

“It’s not about the democracy of letting people decide in a lawful referendum – it’s about the diktat of an independence-obsessed First Minister.”

Scottish Green MSP Patrick Harvie said: "The Bill itself contains no specific commitment to an independence referendum during this parliament, but whether Brexit is eventually imposed on Scotland or not, we believe that such a referendum should take place on that timescale.

“The detail of the Bill needs scrutiny, like the inclusion of a citizenship requirement for the right to vote, despite repeated promises by the Scottish Government to ensure that voting rights are based on residency instead.   

“We respect the fact that some people don’t want to see this debate even take place.

"But those who oppose independence should at least have the willingness to come forward with positive alternatives.

"The status quo is broken and we should not ask Scotland to face the threat of a chaotic Brexit and a hard right Prime Minister, without the power to make our own choices about our own future."

Former Labour MP Pamela Nash, chief executive of Scotland in Union, said: “This is a reckless act by an irresponsible government.

“With a constitutional crisis over Brexit, the very last thing the country and the economy needs is deeper division and greater uncertainty.

“Nicola Sturgeon only cares about putting up barriers between people, but it’s time for her to become First Minister for everyone in Scotland and drop this unwanted plan.

“Only a fifth of voters back her proposal to force a divisive second referendum on the country by 2021, and a third of former Yes voters now want to remain in the UK.”