The First Minister, speaking on Sophy Ridge on Sunday on Sky News, said Westminster “fearing the democratic outcome” of indyref2 was not an “excuse” for changing the rules of such a vote.
Her comments follow reports in the Sunday Times that Liz Truss is planning to pass a new law that would rewrite the rules for a second vote on Scottish independence.
The plans would see a second referendum banned until polls show 60 per cent of Scots backing a new vote for at least a year.
Such a ‘Referendum Act’ would also only guarantee independence if 50 per cent of the entire Scottish electorate voting Yes rather than a simple majority, a bar not met by the No campaign in 2014.
The comments are similar to those made by Alister Jack, the Scottish secretary, while he was serving in Boris Johnson’s Cabinet.
Support for independence in the polls peaked at 58 per cent during the pandemic, but that figure has slid to around 50 per cent in recent months.
The comments also come ahead of a Supreme Court hearing on a prospective referendum bill after Lord Advocate Dorothy Bain QC referred the question to ascertain if legislating for another referendum was within the powers of Holyrood. Oral arguments are to be heard in the case next month.
Ms Sturgeon said: “It is not a sign of strength on the part of Liz Truss to talk about blocking a referendum or, as some reports today suggest, gerrymandering the rules for a referendum.
"That is a sign of fundamental weakness and a lack of confidence in her case for the Union.”
The First Minister said the reported reform would be “a changing of the basic rules of democracy that we have all abided by for our entire lifetimes and long before that”.
She said: "Can you imagine the furore and literal foaming at the mouth that we would have had from the Conservative party if anybody had suggested that for the Brexit referendum.
"Just because you fear losing a democratic contest, it’s not an excuse. It doesn’t make it acceptable to rewrite the rules of democracy, that’s my point here.
"There has never been a positive case for the Union made by those who put forward that case.
"In 2014 they tried and got away with it, to scare people in Scotland. I remember back then there were all sorts of scare stories about all sorts of things.”
Ms Sturgeon also rejected claims that independence was a distraction from the cost-of-living crisis, claiming independence would have provided Scotland the levers to solve the crisis.
She said: “It’s not a distraction and part of my job is to persuade people of that because part of the reason we are in this mess right now is because we are not independent and therefore we don’t have the levers to navigate our way out of that.
"If Scotland was independent, we could already have passed an emergency budget. We’d have powers to reform the energy market to deal with some of the underlying causes of this.”