THERESA May yesterday blocked Nicola Sturgeon’s call for a second Scottish independence vote until at least 2021.
She told her there was no chance of a vote in late 2018 or early 2019 because of the Brexit negotiations and said: “Now is not the time”.
Scottish Tory leader Ruth Davidson agreed, saying Scots should wait to see how the UK was working post-Brexit.
And she set out a timetable making IndyRef2 impossible before the next Holyrood elections in 2021.
But First Minister Ms Sturgeon said: “This is like winding the clock back to the bad old days of Margaret Thatcher.
“History may look back on today and see it as the day the fate of the union was sealed.”
And SNP veteran Alex Salmond accused Mrs May of treating Scotland “like a county rather than a country”.
Scots had already rejected independence in a referendum in 2014.
But earlier this week SNP leader Ms Sturgeon called for a second vote, saying the country was being dragged out of the EU against its will.
Yet a poll this week claimed 57 per cent of Scots would currently vote to stay in the UK.
Striking a blow to hopes of independence, Mrs May said: “We have a bright future together and we need to make sure we are putting our energies into getting the right deal with the European Union.
“This union we have is very precious, we have been joined together for 300 years, I believe in a great future together.”
Mrs May also said all parts of the UK should “work together” to get the best deal after Brexit. The PM said: “My message is very clear — now is not the time. It would be unfair to Scotland, the people of Scotland.
“They would be being asked to make a crucial decision without the information they need to make the decision.”
Responding, Ms Sturgeon said she does not want a referendum now, but when the terms of Brexit are clear and “before it is too late to choose an alternative path".
On Twitter, she added: “A section 30 order must be discussed and agreed now to enable that timescale.
“If the Tories refuse to do so, they would effectively be blocking Scotland's right to choose when the Brexit terms (are) clear.
“This would be undemocratic given @scotgov (the Scottish Government's) clear mandate and also proof positive that the Tories fear the verdict of the Scottish people.”
She then added: “One last point - if PM thinks we won't know terms of Brexit by autumn next year, she must think her own timetable will fail.”
Scottish Secretary David Mundell said it would not enter into “discussions or negotiations” on a request for the legal power to hold a vote.
He said: “This argument isn't about mandates, it's about holding a referendum on established criteria which were set on in the Edinburgh Agreement.
“That established that a referendum must be legal, fair and decisive.
“The proposal brought forward is not fair, people will not be able to make an informed choice.”
Speaking alongside Mr Mundell at a press conference in Edinburgh, Scottish Conservative leader Ruth Davidson said: “We reject conclusively the timetable for a referendum set out by the Scottish Government for a key reason - because it is unfair to Scottish voters.
“We've just come through a referendum campaign where a key complaint among many people was that they did not have the necessary information to help them make an informed decision.
“If we were to keep to the First Minister's timetable this is exactly what would happen in Scotland too.”
'Now is not the time'
Theresa May's full comments on ruling out a second Scottish independence referendum:
Nothing is more important to me than seeing this United Kingdom thrive. Our precious union of nations is the most successful that the world has ever seen.
And we have been joined together as one country for over 300 years. We have worked together, we have prospered together, we have fought wars together.
And we have a bright future. I think there’s a bright future for us all.
That’s why as we embark on the process of a new relationship, a future relationship with the European Union, I’m going to be fighting for every person, every family, every business across the whole of the United Kingdom.
That’s my focus. And I think it should be the focus of us all.
So when the SNP government say that it’s the time to start talking about a second independence referendum, I say that just at this point, all our energies should be focused on our negotiations with the European Union about our future relationship.
And to be talking about an independence referendum would, I think, make it more difficult for us to be able to get the right deal for Scotland and the right deal for the UK.
And, more than that, I think it would not be fair to the people of Scotland because they’d be being asked to take a crucial decision without the necessary information, without knowing what the future partnership will be or what the alternative of an independent Scotland would look like.
So I think, just now, we should be putting all our energies into ensuring that we get that right deal for the UK and the right deal for Scotland in our negotiations with the European Union. That is my job as prime minister.
Right now, we should be working together, not pulling apart. We should be working together to get that right deal for Scotland, that right deal for the UK.
And so, for that reason, I say to the SNP now is not the time.