The First Minister again insisted she was not "bluffing" with her threats of a second referendum and refused to rule out calling it in autumn 2018.
Her predecessor, Alex Salmond, has repeatedly suggested this as a likely date and her comments will fuel speculation of an announcement at next week's SNP conference.
It is thought to be the first time Ms Sturgeon has directly addressed Mr Salmond's proposed timetable for a rerun of the 2014 ballot.
Nicola Sturgeon warns Scotland could hold a referendum next year
I think would be the common sense time for, Scotland to have that choice, if that is the road we choose to go down
Nicola Sturgeon – Scotland First Minister
But the remarks made in a BBC interview sparked fury among opponents who have urged her to "put the country first".
Asked about autumn 2018 Ms Sturgeon told Brexit: Britain’s Biggest Deal: “Within that window, er I guess of when the, the sort of outline of a UK deal, becomes clear on the UK exiting the EU, I think would be the common sense time for, Scotland to have that choice, if that is the road we choose to go down.”
Pressed by presenter Laura Kuenssberg if she "not was ruling out autumn 2018”, Ms Sturgeon replied: “I’m not ruling anything out.”
Sturgeon said ‘I’m not ruling anything out’ when asked about another referendum All the best pictures from the Scotland Referendum Sun, March 5, 2017
More than 3.6m people turned out to vote in the Scottish independent referendum, resulting in a 'No' vote with 55.3%.Here we take a look at the public's reaction.
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Pro-Independence supporters are pictured in Edinburgh, Scotland, on September 19, 2014, as referendum results are announced. Scotland appeared set to reject independence on Friday with 23 out of 32 voting areas declared and the crucial Glasgow region having given its result
The power to hold a referendum is reserved to the UK Government.
Holding one in Scotland requires Westminster to grant a 'section 30' order.
Mrs May has refused to be drawn on whether she will reject any demand for one, with Whitehall source suggesting they are focused on preventing any request coming.
Earlier this week former SNP deputy leader Jim Sillar said he would not vote for independence if it would result in rejoining the EU.
Mr Sillars, 79, who played a leading role in 2014's Yes campaign, declared he did not want to be run by "an unelected, self-serving elite" in Brussels.
Scottish Tory leader Ruth Davidson hit out Ms Sturgeon's latest comments saying it proved the "SNP is hell bent on taking Scotland back to another divisive independence referendum".
Ms Davidson added: "She knows that a referendum would inflict further damage on Scotland's economy.
"It is therefore deeply irresponsible for the First Minister of Scotland to cast this cloud of uncertainty over our future.
Scottish Tory leader Ruth Davidson has hit out Ms Sturgeon's latest comments
"She needs to put the country first for once. People in Scotland don't want a second referendum, and the SNP doesn't have a mandate for one.
Rather than cast our future under further doubt, Nicola Sturgeon needs to act like a First Minister, provide some certainty for Scotland, and rule it out."
Scottish Labour leader Kezia Dugdale added: “This is yet another attempt by Nicola Sturgeon to sow division and uncertainty, at a time when the country needs to pull together more than ever.
“The First Minister has been all over the place – one week she threatens a vote, the next week she backs away from one.
"Nicola Sturgeon could provide much needed clarity on Scotland's future by ruling out another independence referendum altogether."
Scottish Labour leader Kezia Dugdale said Sturgeon is sowing ‘division and uncertainty’
Tonight's interview – recorded at the end of February – also sees Ms Sturgeon reject suggestions she is "bluffing about holding a referendum."
She said: “Well, I’m not and I never have been and, you know, I always think that sometimes kind of says more about them than it says about me because it, it suggests that there are politicians in Westminster who think Brexit and all of this is some kind of game.
"It’s not a game, it’s really, really serious and the implications for the UK are serious and the implications for Scotland are serious."
Brexit: Britain’s Biggest Deal is broadcast tonight at 9pm on BBC Two