Ian Rankin has insisted that his comments about JK Rowling writing a crime novel were made in jest.

Speaking at the Edinburgh book festival, the Scottish author claimed that his wife Miranda had visited a cafe and spotted the Harry Potter writer making notes for a detective plot.

"This is a joke that got out of hand," Rankin told The Guardian. "There were 600 people in the audience, and only one person didn't laugh."

A spokeswoman for Rowling's literary agent, Christopher Little, added that the rumours are "unfounded".

She continued: "JK Rowling is taking a well-earned break following the English language publication of Harry Potter and the Deathly Hallows and there are no firm plans as yet as to what her next book may be."