JK Rowling has announced she is set to release a previously unseen fairy tale story online for children in lockdown.

Revealing details of The Ickabog in a lengthy thread on Twitter, the author made it clear the story is nothing to do with her most famous creation, Harry Potter, but a stand-alone tale originally read to her own children at bedtime.

Written more than 10 years ago, it is a story Rowling says she always intended to publish, but never got round to it after writing two novels for adults after the final book in her wizarding series.

In a statement announcing the details on her website, the writer says The Ickabog is “a story about truth and the abuse of power”, although answering the obvious question, “isn’t intended to be read as a response to anything that’s happening in the world right now”.

The only other people who know The Ickabog are her two youngest children, she says, and she had begun to think of it as simply a family story.

However, with the UK in lockdown due to the coronavirus pandemic, Rowling searched for the manuscript in her attic and has decided to serialise the story for free online, starting with the first two chapters at 3pm today.

She has also called on children to provide illustrations for a physical book, to be published in November.

Rowling says royalties from sales of The Ickabog will go to projects assisting groups particularly impacted by the COVID-19 pandemic.

Before that, there will be a total of 34 daily instalments online, with translations in other languages as well as English, each weekday on a new Ickabog website up until Friday 10 July.

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In her statement, Rowling says: “The idea for The Ickabog came to me while I was still writing Harry Potter. I wrote most of a first draft in fits and starts between Potter books, intending to publish it after Harry Potter And The Deathly Hallows…

“Over time I came to think of it as a story that belonged to my two younger children, because I’d read it to them in the evenings when they were little, which has always been a happy family memory.

“A few weeks ago at dinner, I tentatively mooted the idea of getting The Ickabog down from the attic and publishing it for free, for children in lockdown.

“My now teenagers were touchingly enthusiastic, so downstairs came the very dusty box, and for the last few weeks I’ve been immersed in a fictional world I thought I’d never enter again.

“As I worked to finish the book, I started reading chapters nightly to the family again. This was one of the most extraordinary experiences of my writing life, as The Ickabog’s first two readers told me what they remember from when they were tiny, and demanded the reinstatement of bits they’d particularly liked (I obeyed).”

Rowling says the story was written as a read-aloud book but should be suitable for children aged seven to nine to read by themselves.

This is not the first initiative launched by the author for children in lockdown – she also set up the Harry Potter At Home digital hub to provide entertainment for youngsters.

And at the beginning of May, Harry Potter himself, Daniel Radcliffe, returned to the wizarding world to recite the first chapter of the first ever book, Harry Potter And The Philosopher’s Stone, in an ongoing storytelling project also involving stars such as Stephen Fry and David Beckham.

On Sunday, Rowling offered to pay a year’s salary to the person responsible for a tweet from the Civil Service’s official account, which appeared to accuse Boris Johnson of being an “arrogant, offensive truth twister”.

The tweet, which was retweeted more than 32,000 times before it was deleted, was posted shortly after the prime minister used his Downing Street press conference that day to defend his chief adviser Dominic Cummings.

Cummings later went on to give his own press conference on Monday after the backlash to his lockdown trip to Durham from London continued to grow.