A second referendum on Scottish independence will be the result of "sheer intransigence" on the part of Theresa May's government, Nicola Sturgeon has said.
The First Minister has insisted she has a "cast-iron mandate" to call another vote, justified by the EU referendum result and the SNP's victory in May's Holyrood elections.
Writing in The Times newspaper on Tuesday, she said she had chosen to hold off exercising her mandate immediately to explore other options to protect Scotland's place in Europe.
With the majority of Scots voting to stay in the EU, Ms Sturgeon has put forward proposals for a "differentiated deal" which could see Scotland remain part of the European single market through membership of the European Economic Area.
But she said the UK Government's approach remained "its way or no way".
Speculation is now growing that Ms Sturgeon will call a second independence vote when Article 50 is triggered in March.
Mrs May will travel to Scotland later this week to address the Scottish Conservative party conference in Glasgow, while the First Minister will speak to SNP supporters at its conference in Aberdeen in mid-March.
Ms Sturgeon wrote: "We accepted, reluctantly, that we would leave the EU, but argued for the UK to stay in the single market or, if that was not possible, for the UK to seek as part of its negotiation an outcome that would allow Scotland to do so, and to agree to a rebalancing of power across the UK to take account of the post Brexit landscape and enable any different decisions that Scotland might want to take.
"Instead of meeting us halfway, however, the UK Government's approach has been 'its way or no way'."
She added: "If an independence referendum does arise, it will not be down to bad faith on the part of the Scottish Government, but to sheer intransigence on the part of the UK Government.
"It is not too late for the UK Government to change course, but time is running out."
Scottish Labour and the Tories said most people in Scotland do not want another referendum.
The Scottish Conservative chief whip John Lamont said: "People are growing increasingly tired of the First Minister's constant threats over a second referendum.
"The truth is that most Scots don't want to go back to more division and uncertainty.
"Nicola Sturgeon would be better served concentrating on the day job, and focusing on getting the right deal for Scotland and the whole United Kingdom.
"She should act as the First Minister of Scotland, not as a rabble-rouser for a referendum most people don't want."
Scottish Labour Westminster spokesperson Ian Murray said: "This latest threat from Nicola Sturgeon is irresponsible economic vandalism.
"Our economy is already in trouble following the Tories' reckless Brexit gamble, and the very last thing we need is more uncertainty for employers, workers and markets.
"In 2014, more than two million Scots voted to reject separation and the polls are quite clear that Scots do not want another referendum. The SNP has no mandate for a divisive second independence referendum.
"And if Nicola Sturgeon tries to push one through, Scottish Labour will firmly oppose it in the Scottish Parliament.
"The SNP is obsessed with seeking to divide our country, rather than fixing the problems in our hospitals and schools.
"Labour believes that together we're stronger, which is why we will never support Scottish independence."