JK Rowling has sparked rumours that she is writing a new Harry Potter book with a series of cryptic tweets.

The author first alluded to a book she is working on via Twitter, writing: “Very busy at the moment working on a novel, tweaking a screenplay and being involved in @lumos campaigns. Back when I've finished something!”

When asked what for a clue on what she's working on, she wrote: “See, now I'm tempted to post a riddle or an anagram. Must resist temptation... must work...” 

Rowling added: “Cry, foe! Run amok! Fa awry! My wand won’t tolerate this nonsense”

The final post, which was retweeted over five thousand times, caused much speculation that the wand comment meant she is writing a new book about wizard Harry Potter.

Watch this space!