Jk Rowling has started work on the third instalment of the 'Fantastic Beasts' franchise.

The best-selling author wrote the 2016 film 'Fantastic Beasts And Where To Find Them', and with the second movie in the series due out later this year, Rowling has revealed she's already busily working away on another film.

In a Q&A on her own website, Rowling shared: ''I've just finished the fourth Galbraith novel, 'Lethal White', and I'm now writing the screenplay for 'Fantastic Beasts 3'.''

Despite being best known for her 'Harry Potter' work, Rowling also writes crime stories under the pseudonym Robert Galbraith.

During the interview, the acclaimed author spoke in detail about her role with the franchise, revealing that she's most influential during the early stages of the creative process.

She said: ''Warner Bros. and David Yates, the director, have always let me have my say, though not necessarily the final word.

''That's true of all the producers, of whom I'm only one: our input is taken seriously but it is very much a collaborative effort. The director is ultimately responsible for everything that's seen on the screen.''

Meanwhile, Eddie Redmayne - who stars as Newt Scamander in the 'Fantastic Beasts' franchise - previously admitted to stealing some ideas from the likes of Daniel Radcliffe and Emma Watson, who appeared in the 'Harry Potter' series.

Asked whether he rewatched the 'Potter' films ahead of starring in the prequels, the Academy Award-winning star explained: ''I didn't. They are always on. I did watch moments, like the wand stuff. There is a sense that every actor is like, 'One day, I'll get my wand moment.'

''I got my wand moment, and I got stage fright. I got awkward. I didn't know what to do with it. In the end, I watched Dan Radcliffe, Ralph Fiennes, and Emma Watson. I definitely stole, and thieved.''