Scotland’s first minister has said autumn 2018 would be a “common sense” date for any second independence referendum.
Nicola Sturgeon continued to insist, however, that no final decision had yet been made on holding such a vote.
In a BBC interview, she said she would take things forward at “the pace that I think is right for the country”.
Ms Sturgeon has previously said another referendum is “highly likely” following last year’s Brexit vote.
Scotland voted by 62% to 38% to remain inside the EU, and the Scottish government argues that access to the single market after Brexit is vital to the country’s interests.
Scottish ministers have put forward proposals they claim could achieve this, but have accused the UK government of “intransigence” on the issue.
In a recent speech in Edinburgh, Ms Sturgeon said a second independence referendum may become a “necessary” way of protecting Scotland’s interests.
Interviewed by BBC political editor Laura Kuenssberg for a BBC documentary to be broadcast on Thursday, she gave her clearest indication yet about the possible timing of such a vote.
Asked if autumn 2018 was a likely date, she replied: “Within that window, of when the outline of a UK deal becomes clear and the UK exiting the EU, I think would be common sense time for Scotland to have that choice, if that is the road we choose to go down.”
Asked if that meant she was not ruling out autumn 2018 as a possible date, she said: “I’m not ruling anything out, I’m going to continue to take things forward at the pace that I think is right for the country.”
Analysis by BBC political editor Laura Kuenssberg
At Westminster and Holyrood in recent months there’s been a building sense that Nicola Sturgeon has made up her mind to call a vote.
If she is now willing to discuss the timing of a second vote in public, consideration of another independence referendum is far beyond the hypothetical.
The crucial facet of that calculation is that the SNP believes its best chance of winning is before the EU negotiations are complete.
But also, it’s up to the Westminster government to permit another referendum. There are huge risks for them in denying it, but ministers in London certainly would not grant a vote at the time of the SNP’s choosing without a fight.
Scotland voted to stay part of the UK by 55% to 45% in the 2014 independence referendum.
Ms Sturgeon’s predecessor as first minister, Alex Salmond, has already predicted that a second independence referendum would take place in autumn next year.
While the SNP does not hold an overall majority at Holyrood, it could count on the support of the Scottish Greens if the Scottish Parliament voted on holding a new referendum.
Permission to hold such a vote, however, would have to be granted by the UK government at Westminster.
Prime Minister Theresa May has so far declined to be drawn on whether her government would allow a second referendum.
In her speech to the Scottish Conservative Party conference earlier this month, Mrs May accused the SNP of being “obsessed with its own priority of independence” to the detriment of devolved public services like education and health.
Nicola Sturgeon’s interview was recorded for the BBC documentary Brexit: Britain’s Biggest Deal – to be broadcast on BBC Two in England, Wales and Northern Ireland at 21:00 and on BBC Two Scotland at 23:15 on Thursday.
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