IT WILL undoubtedly be Harry Potter's biggest adventure yet.

The fictional hero of an Edinburgh children's author has already made short work of John Grisham, Jeffrey Archer and Terry Pratchett in the bestsellers' lists and is set to take on Hollywood.

Joanne Rowling's negotiations with Warner Brothers have resulted in the film rights for the two hugely popular Harry Potter books, written in a coffee shop, being bought for a seven-figure sum.

A screenwriter is being recruited to adapt the novels into a live-action production.

Last night, Rowling, a single mother, said of her own fairy-tale rise to literary - and now movie - success: "This is beyond my wildest expectations.

I am stunned and delight-ed."

The tales of the 11-year-old orphan boy with the powers of a wizard have caught the public imagination. More than 200,000 copies of Harry Potter and the Philosopher's Stone and Harry Potter and the Chamber of Secrets have been sold in the UK.

Its publisher, Bloomsbury, has produced an adult-style edition to appeal to the growing number of Harry's grown-up followers.

The author, who writes under the name JK Rowling, created her hero while sitting in Edinburgh coffee bars as her baby daughter slept in a pushchair at her side.

Rowling, 33, a former teacher, began writing to pass the time when she moved to the capital after her marriage broke up.

She said: "I am in a kind of stunned relief. The talks went on for months and months and at some stages I thought it would never happen.

"It will be a incredible experience to see in real life what I have seen inside my mind. It will be quite disorientating, but wonderful.

"The whole thing has gone beyond my wildest expectations as my life's ambition was just to support myself. I only thought about books and if there had never been a film, I would have been happy.

"I think Warner Bros will do a good job and be true to the character. Other children's films they have produced helped sway me."

David Heyman, of Heyday Films, the production partner with Warner Bros which has bought the options, said Harry Potter's unique appeal was the key to the deal.

He said: "These are really family adventures in the truest sense, with stories and writing than can be appreciated by readers of all ages.

"I know adults who bought the book initially for their children to take on holiday - it ended up ripped apart because so many people wanted to read it. Although the books are aimed at the nine to11 age range, there is something a wee bit special here that goes far beyond that.

"It will be a live-action film and I hope the part of Harry Potter will be an attractive one for young actors."

Mr Heyman said he was still unsure if he would make a single film from the two books or begin a cinematic adventure series. Rowling has said there will be seven Harry Potter adventures.

Lorenzo di Bonaventura, president of Warner Bros' worldwide theatrical production, said: "These books have a terrific following in Great Britain and America, where Harry Potter and the Philosopher's Stone has just been released.

"We look forward to seeing Heyday Films' adaptation of this material for the screen, where it can be embraced by fans on both sides of the Atlantic."

Rowling's third book, Harry Potter and the Prisoner of Azkaban, will be published next summer. She is about to embark on a US tour and a website has been set up to allow readers an insight into how future books are developing.

The GBP 100,000 advance for Rowling's first novel put her ahead of another bestselling author, John Grisham, whose debut book The Firm, cost his publisher GBP 70,000.

Copyright 1998 The Scotsman Publications Ltd.