Last December, the Scottish Government had proposed plans that would have allowed Scotland to remain in the single market even after the rest of the UK leaves.

Voters north of the border had backed remaining in the EU by 62 to 38.

May has always insisted that any deal would be for the whole of the UK.

In a final ultimatum, Sturgeon said unless there was considerable movement from Whitehall, voters in Scotland would be given a choice between “a hard Brexit and becoming an independent country”.

That vote would, she said, take place between the autumn of 2018 and the spring of 2019, when there is a better understanding of the nature of the deal the UK has achieved with the EU.

The First Minister said: “The Scottish Government’s mandate for offering this choice is beyond doubt. So next week I will seek the approval of the Scottish Parliament to open discussions with the UK Government on the details of a Section 30 order – the procedure that will enable the Scottish Parliament to legislate for an independence referendum.

“The UK Government was clear in 2014 that an independence referendum should be, in their words, ‘made in Scotland, by the people of Scotland’. That is a principle that should be respected today. The detailed arrangements for a referendum – including its timing – should be for the Scottish Parliament to decide.

“It is important that Scotland is able to exercise the right to choose our own future at a time when the options are clearer than they are now, but before it is too late to decide on our own path. By the time a choice comes to be made, there must be greater clarity about Brexit and its implications for us.

“It is just as important that there is clarity about the implications of independence. And there will be.

“We will be frank about the challenges we face and clear about the opportunities independence will give us to secure our relationship with Europe, build a stronger and more sustainable economy and create a fairer society.

“If I ruled out a referendum, I would be deciding, completely unilaterally, that Scotland will follow the UK to a hard Brexit come-what-may, no matter how damaging to our economy and our society it turns out to be.

“That should not be the decision of just one politician – not even the First Minister.  It will be decided by the people of Scotland. It will be Scotland’s choice.”

The First Minister said she would ask the Scottish Parliament to back her request for a Section 30 order from Westminster.