Nicola Sturgeon has put Holyrood and Westminster on an apparent collision course after the Scottish First Minister published plans that could lead to a second independence referendum.
The Scottish Government has launched a consultation on a new draft Referendum Bill, with Ms Sturgeon insisting voters north of the border should be given the chance to consider the issue afresh after the Brexit vote.
While the UK narrowly voted to leave the EU, almost two-thirds of Scots who took part in the ballot wanted to remain part of the bloc.
The First Minister has said she will put forward specific proposals aimed at keeping Scotland in the single market even if the rest of the UK leaves, as well as for ''substantial additional powers'' for Holyrood as part of the UK's Article 50 negotiations, including over international deals with other nations and immigration.
But she has stressed the Scottish Parliament must be able to consider the option of an independence referendum "if it becomes clear that it is the best or only way of safeguarding Scotland's interests".
Such a vote would then take place before the UK formally quits the EU, Ms Sturgeon said.
Prime Minister Theresa May, however, insists there is no mandate for Scotland to have another ballot on independence after the country voted by 55% to 45% in favour of staying part of the UK in September 2014.
The consultation states that if the SNP Government does formally introduce a Referendum Bill to Holyrood " it would be expected that a section 30 order would be sought and agreed, as in 2014" to make the vote legally binding.
Scottish ministers will reach a conclusion on whether to ask MSPs to approve a Bill "in the light of developments over the coming months".
Ms Sturgeon said: "My priority is clear - we will do everything we can to protect Scotland's interests.
"The damage to jobs and Scotland's economy that will be caused by Brexit - especially a hard Brexit - is now plain to see.
"We will continue to work UK-wide to seek to avert a hard Brexit and we will also bring forward proposals that seek to protect our place in the single market, even if the rest of the UK leaves.
"However, if we find that our interests cannot be properly or fully protected within a UK context, then independence must be one of the options open to us and the Scottish people must have the right to consider it."
Under the proposals, it is expected that Scots would be asked the same question posed in 2014: "Should Scotland be an independent country?"
The document, published online, also sets out plans for a second poll to be decided by a simple majority, as was the case two years ago, while the franchise would again see EU citizens living in Scotland and those aged 16 and 17 able to vote.
But a Number 10 spokesman dismissed the need for another independence referendum, saying: " The Prime Minister and the Government does not believe that there is a mandate for one.
"There was one only two years ago. There was an extremely high turnout and there was a resounding result in favour of Scotland remaining in the UK."
When the 2014 vote was proposed, "both sides agreed to abide by that referendum", the spokesman added.
Asked if UK ministers would reject a call for a second referendum from the Scottish Government, he stated: "There has not been a call."
But 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 consultation runs until January 11 next year.
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, t he 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."