Author Philip Pullman said he was sorry to learn that the director of the film version of one of his award-winning books has quit.

New Line Cinemas, which made The Lord of the Rings, is making The Golden Compass, an adaptation of Northern Lights, the first book in the His Dark Materials trilogy.

The production has suffered a number of setbacks, the latest being the resignation of director Anand Tucker, who directed Hilary and Jackie, the Jacqueline du Pr biopic. He has been replaced by About a Boy director Chris Weitz, who previously worked on the project but stepped down because he found the technical challenge too much.

Mr Pullman, who lives in Cumnor, said: "I'm sorry to say goodbye to Anand Tucker, whom I liked, but glad that the film will go forward in such good shape.

"The books are my business, but once I've sold the rights to a film company, the films aren't.

"I know some readers have criticised me for this attitude they think I should supervise every shot and fight for every word to be retained. Others have been cross about the prospect of any film at all. The fact is that the books will remain unchanged, whatever happens."

Last month, more than 3,500 girls came to Oxford to audition for the part of Lyra, the girl who travels to the Arctic to save her best friend.

Auditions in Cambridge and the Lake District attracted only 1,500 hopefuls, but the Oxford auditions, at the Examination Schools, in High Street, were more popular because the city is the home of Mr Pullman.

New Line Cinema spokesman Alexandra Ruane said: "Callbacks from the various auditions are still taking place, and the actress who will play Lyra will be chosen before filming starts in the Autumn or by November."