Nicola Sturgeon has refused to say whether she would call off her push for a second independence referendum by 2021 if Brexit does not take place.
The first minister is seeking a vote on independence before the next Scottish election if the UK leaves the EU.
Asked on Friday what would happen if Brexit was halted, she said she would set out her views at that stage.
Ms Sturgeon said she would not “narrow Scotland’s options” because the country needed “maximum flexibility”.
She suggested that “the way Scotland has been treated” could be grounds for another independence referendum – as could Boris Johnson becoming prime minister.
Ms Sturgeon was speaking to BBC Scotland ahead of the SNP’s conference, which opens in Edinburgh on Saturday.
The UK government has already ruled out granting permission for a referendum before the next Holyrood election in May 2021.
And the Scottish Conservatives said Ms Sturgeon’s latest comments showed that she “wants to press on with her break-up plans come hell or high water”.
The SNP’s manifesto for the 2016 Holyrood election stated that another vote on independence should be held if there was a “material change of circumstance”, such as Scotland being taken out of the EU against its will.
However, Ms Sturgeon told the Good Morning Scotland programme that “many people would say there’s been a big material change of circumstances already in the way Scotland has been treated over the past few years”.
The first minister, who has also called for another Brexit referendum, said she could only currently make plans on the basis that the UK is still going to leave the EU.
She added: “If that doesn’t happen then I guess we’ll be having another discussion and I’ll give my views on what we do then.”
She later told BBC Scotland’s political editor, Brian Taylor, that she was “not going to narrow Scotland’s options” because “we could be facing Boris Johnson as prime minister within the next few months”.
“Scotland needs to have maximum flexibility and maximum room for manoeuvre to get itself onto the right path,” the first minister argued.
“I think Boris Johnson as prime minister would send not just people in Scotland, but many people across the whole of the UK, into utter despair.
“Boris Johnson, not single-handedly but largely, is responsible for the complete mess the UK finds itself in.”
Nicola Sturgeon has said she wants to hold a second referendum on Scottish independence by 2021 if the country is taken out of the EU.
The first minister intends to have Scottish Parliament legislation that could pave the way for a referendum in place by the end of this year.
But she has also made clear that Westminster’s approval would be needed before any referendum is actually held to ensure its legal status is “beyond doubt”.
Ms Sturgeon has not yet made a fresh request for this consent – but has indicated that she plans to do so either at the end of this year or the beginning of 2020.
Theresa May’s deputy, David Lidington, explicitly ruled out that request being granted when he spoke to the media during a visit to Glasgow on Thursday.
Mr Lidington said there was “no evidence” of a surge in support for independence since the last referendum in 2014, which he argued had settled the issue for a generation.
Ms Sturgeon responded by saying Mr Lidington was a member of a UK government which might not be in office “in a matter of weeks”.
She added: “They’re not exactly known for consistency. This is the UK government who said the UK would definitely be out of the the EU on 29 March.
“They are also a government frankly that it is impossible to have a meaningful negotiation with. They have zero authority and zero credibility which is why I decided not to bother trying to negotiate with them at the moment.”
Responding to her comments, Scottish Conservative MSP Adam Tomkins said: “This is proof that Nicola Sturgeon wants to press on with her break-up plans come hell or high water.
“Whether there’s a hard Brexit, a soft Brexit or no Brexit at all – the first minister will make this all about independence.
“The voting public saw through this scam last time and will do so again. It’s a shameless approach – Nicola Sturgeon isn’t even pretending to care about Brexit any more.”
Scotland rejected independence by 55% to 45% in the 2014 referendum – with opinion polls suggesting support for independence remains largely unchanged five years later.
Ms Sturgeon initially called for a second referendum after the Brexit vote in 2016, but put her plans on hold after the SNP lost 21 seats in the general election the following year.
What did Ms Sturgeon say on Wednesday?
The first minister said she wants to hold a second referendum on Scottish independence by 2021 if the country is taken out of the EU.
She hopes a “framework Bill” – Scottish Parliament legislation setting the rules for any future referendum – will be in place by the end of this year.
She told the Scottish Parliament: “We do not need a transfer of power such as a Section 30 order to pass such a framework Bill, though we would need it to put beyond doubt or challenge our ability to apply the bill to an independence referendum.”
The first minister also predicted: “If we are successful in further growing the support and the demand for independence, then no UK government will be able to stop the will of the people or stop that will being expressed.”
She announced she wants cross-party talks with opposition leaders about Holyrood’s powers, while a Citizens’ Assembly will be set up to examine wider questions on Scotland’s future.
Writing in the Scotsman newspaper after Ms Sturgeon’s announcement, SNP veteran Kenny MacAskill – the former justice secretary – claimed that independence supporters who now expect an immediate referendum are “delusional”.
He also accused the SNP of “fiddling while Rome burns” and argued that Ms Sturgeon’s “heavily caveated” statement “confirmed what many have long thought, which is that she’s not planning to try for independence before 2021”.
But Ms Sturgeon denies that her statement was an attempt to appease independence activists who want a referendum sooner rather than later, and has insisted that: “The timing is not to do with the SNP conference.”