Oxford author Philip Pullman is positive a sequel will be made to the controversial movie The Golden Compass.

He spoke out after film industry sources cast doubt on a movie version of The Subtle Knife being given the go-ahead.

The Golden Compass was the sixth most successful film at the UK box office last year, grossing £26m, but it took only $70m (£35.05m) in the United States, due to a boycott by some Christians.

Internationally, however, the film version of Northern Lights, the first instalment of Mr Pullman's His Dark Materials trilogy, took $300m (£150.2m) and Mr Pullman says the sequel could still go ahead.

He told the Oxford Mail: "It is quite possible that a sequel will happen but, as everyone knows, the film did not do well in the box office in America and that has a large effect on people's plans. I spoke to the producers last week and they told me about the latest developments.

"They are getting a script together and they have plans to get things going - in time all things are possible and I feel quite positive about it."

Mr Pullman said he hoped there would not be too long a delay before work started on the sequel because Dakota Blue Richards, the 12-year-old star of The Golden Compass, was growing up quite quickly. He added that making a film was a very different, and far more expensive, process to writing a book and having it published.

"Making a film costs millions of dollars and the people involved have to hesitate and think hard about the best way of doing things," Mr Pullman added.

Some scenes for The Golden Compass were shot in Oxford and the film picked up an Oscar for the best visual effects.

Former Bartholomew School pupil Ben Morris, 37, and his company Frame- store, worked on the film and he collected the award for the digital effects used in the film, including giant polar bear Iorek Byrnison.

When The Golden Compass was released last year, New Line Cinema had high hopes for the trilogy as the new The Lord of the Rings, and the sequel was due to be released by the end of 2009.

Michael Gubbins, editor of Screen International, said it was unlikely the sequel would be brought out by next year in a tough box office environment featuring 'trilogy congestion'.

Prince Caspian, the second instalment of CS Lewis's Narnia tales, came out in May and the film took $56m in the United States in its first weekend. Pre-production for The Voyage of the Dawn Treader has started, with the film due out in 2010.

Since the release of The Golden Compass, New Line has merged with Warner Brothers. No-one from Entertainment, the UK distributor, was available for comment.

Oliver Odell, of Oxford city centre management company OX1, said: "We would like to see a sequel - it raises Oxford's profile."

Earlier this year, hundreds of Pullman fans turned up at Oxford town hall to hear him read from his new book, Once Upon A Time in the North, which features characters from His Dark Materials.