The former first minister made the claim in her autobiography, which was released earlier than planned on Monday.

Sturgeon said that her “life has been about” the campaign for Scottish independence.

READ MORE: Seven things we learnt from Nicola Sturgeon’s autobiography Frankly

In Frankly, the SNP MSP reflects at length on her failures to secure a second referendum and the intransigence of the UK Government.

On the book’s final page, Sturgeon said: “I still desperately want Scotland to be independent. I am also confident that it will happen.

(Image: PA)

“I predict that in 20 years, perhaps sooner, the UK in its current form will no longer exist. What will emerge in its place will be stronger, healthier and more democratic.

“An independent Scotland, a more autonomous Wales and a reunified Ireland will join England, enjoying the benefits of the home rule it will gain as a result, in a new British Isles confederation of nations.”

READ MORE: Alex Salmond ‘did not read’ 2014 Scottish independence paper, Nicola Sturgeon says

She said that “nothing” would stop her from “playing my part in trying to bring that about, adding: “For as long as I have breath in my body, I will fight for a fair, equal, inclusive, outward-looking Scotland; an independent country, relatively small in size perhaps, but with the potential to make a big, positive impact on the world.

“That, after all, is what my life has been about.”