Nicola Sturgeon has insisted she would have no right to rule out holding a second independence referendum if polls produce "strong and consistent" evidence that the majority of Scots want to leave the UK.
The Scottish First Minister said she respected the result of last year's ballot, which saw voters reject independence by 55% to 45%.
She warned David Cameron that cuts from Westminster, together with the planned renewal of the Trident nuclear deterrent and other factors, could see support for independence rise.
Two polls since last September's referendum have suggested a majority of Scots want to exit the Union.
With support for the SNP continuing to grow, there has been constant speculation about when a new vote on the issue could take place.
Ms Sturgeon said: "To propose another referendum in the next parliament without strong evidence that a significant number of those who voted No have changed their minds would be wrong and we won't do it.
"It would not be respecting the decision that people made."
But the SNP leader added: "Over the next few years, as the Tories impose even deeper cuts, press ahead with Trident renewal and fail to honour in full the vow of more powers for our Parliament, I think support for independence will continue to rise.
"So let me also be clear about this. If there is strong and consistent evidence that people have changed their minds and that independence has become the choice of a clear majority in this country, then we have no right to rule out a referendum and we won't do that either.
"No one has the right to stand in the way of democracy."
She spoke out as she addressed the SNP conference in Aberdeen - the largest gathering the party has ever staged.