Ms Sturgeon said they are “running scared” of the facts on independence and the UK’s “abysmal” performance compared to other nations.
On Tuesday, the Scottish Government published a paper comparing the UK with other nations Ms Sturgeon claimed are “wealthier, fairer and happier”.
She said: “The Tories and Labour have completely failed to engage with that point because they know it is true and because they can see how threadbare the case for continued Westminster rule over Scotland has become.
“They simply have no answer, so instead of engaging in that debate they prefer to engage in the politics of deflection, talking about issues of process when on the issues of substance the sands are shifting beneath their feet.
“No matter how hard the Westminster parties try and run away from the debate, they cannot dodge reality.
“The people of Scotland have secured a cast-iron democratic mandate to decide their own future – and neither Boris Johnson nor any other UK prime minister has the right to block that mandate.”
The Scottish Government is in a constitutional stalemate over a second independence referendum, with the UK government maintaining opposition to the idea.
Ms Sturgeon has hinted that she may seek a vote without a section 30 order – where powers are formally transferred to the Scottish Government to hold a referendum.
“With the publication of this week’s paper, the campaign for an independence referendum has now begun in earnest, and I am determined to deliver the legal, constitutional referendum the people of Scotland have voted for,” she said.
However, a UK government spokesperson insisted: “Now is not the time to be talking about another referendum.
“People across Scotland rightly want and expect to see both of their governments working together with a relentless focus on the issues that matter to them, their families and communities.
“That means tackling the cost of living, protecting our long-term energy security, leading the international response against Russia’s invasion of Ukraine and growing our economy so that everyone has access to the opportunities, skills and jobs for the future.”