JK Rowling has revealed plans to pen many more crime thrillers and create "a series" that will run for longer than her hugely successful seven Harry Potter books.

The novelist, who has written two whodunnits under the pen name Robert Galbraith, says she loves the crime genre because she can create as many tales as she likes for her character rather than be tied by a single storyline.

Her comments come after her second crime novel featuring detective Cormoran Strike, The Silkworm, topped the Sunday Times bestseller list last month.

Speaking at the Theakstons Old Peculiar Crime Writing Festival in Harrogate, North Yorkshire, the multi-millionaire author said she hoped to write "more than" seven books about the detective.

She said: "It's pretty open ended. I really love writing, so I don't know that I've got an end point in mind.

"One of the things I love about this genre is unlike Harry Potter, where there was a through line, where there was an overarching story, a beginning and end, you are talking about discreet stories. So while a detective lives, you can keep giving him cases."

The best-selling author, who has been widely credited with helping to get a new generation of children reading with her blockbuster Harry Potter series, said she decided to use a pseudonym for her latest series to prove herself as a writer.

She said: "I wanted to prove to myself that I could get a book published on the merits of the book.

"A friend of mine said, 'Why did you need validation?', and I think possibly you need to be a writer to understand why.

"I had known for a long time that I had this character in my mind, and that I wanted to write a detective series and part of me hoped that I might be able to keep it long enough, kept the story going long enough to establish a series.

"I just wanted something, I suppose, just for me."

And Rowling revealed she has always been a huge fan of crime novels and drew inspiration from the genre for her Harry Potter series.

She said: "I love crime. I've always loved it. I read a lot of it and I think in many ways, and I think the Harry Potter books in many ways are whodunnits in disguise.

"I enjoy the golden age (crime) book. That's very much what I was trying to do with these books - to take that finite number of suspects - the genuine whodunnit style, but make it very contemporary, make it up to date and make sure this is a credible person and a credible back story."