Roman Polanski is putting the finishing touches to his forthcoming film from his prison cell in Switzerland, his friend and colleague Robert Harris said yesterday at The Times Cheltenham Literature Festival.

Harris, who wrote the screenplay for the film, said that the director is making decisions about The Ghost so that it will be ready for its scheduled premiere at the Berlin Film Festival in February. Polanski, who is fighting extradition to America where he is wanted for raping a 13-year-old girl in 1977, recently gave instructions about the film score to Alexandre Desplat, the composer best known for writing music for The Queen and The Curious Case of Benjamin Button.

The director, 76, was arrested in Zurich on September 26 after 31 years on the run from the American authorities. He admitted having sex with Samantha Gailey, a model he hired for a photoshoot, but jumped bail in February 1978 when he discovered that he would face a lengthy prison sentence despite negotiating a plea bargain. Harris, who was in Cheltenham to publicise his book Lustrum, said that The Ghost would be completed in accordance with Polanski’s wishes. The director had finished editing the film, which stars Pierce Brosnan as a British prime minister accused of war crimes, on the day of his arrest.

Harris said: “He can make his wishes known from his cell. I don’t think he can make phone calls, but he can communicate. What people think of the film is another matter. Whether the film can rise above the circumstances in which the director now finds himself I don’t know. We will test to the upper limits the notion that there’s no such thing as bad publicity.”

Polanski’s arrest has divided public opinion. Most American commentators have welcomed the opportunity to bring him to justice, but there was an outcry in France, where he has lived without fear of extradition because of his French citizenship.

President Sarkozy said that he hoped for a “speedy resolution”.

Harris said that he does not condone Polanski’s crime, but believes that the story is more complicated than some commentators have described it. Polanski pleaded guilty to unlawful sexual intercourse in a deal with prosecutors in exchange for them dropping charges of rape, drugging and sodomy, which would have carried a life sentence. But he fled America when he discovered that he would still serve time in prison.

Harris, who is best known for historical novels such as Fatherland and Imperium, said: “He was left with little choice but to flee. I’ve got to know him very well. He’s got to know my children. I know his children. He has effectively been on probation for 32 years. For this to happen to him now . . . it seems to me to be bad treatment, especially as the victim herself says that she doesn’t want him to be pursued any further.”

He said that he did not worry about being tainted by association with Polanski and only hoped that his friend would be allowed to fight extradition from outside prison so he can see his family.

The author said:“These proceedings do drag on for the best part of a year. He’s a tough man. He’s been through a lot. If anyone can survive it, he can.”

Polanski’s life has been beset by tragedy. His mother was killed in Auschwitz, and in 1969 his pregnant wife, Sharon Tate, was murdered by the Manson Family.

Harris said that Polanski wanted the film to be completed even if he is in prison. It is a nightmare looming that the director might be in jail at the time [of the film’s release] but we will just have to cope with this as the situation develops. I’m sure he would want the film to go ahead, having worked on it for two years.”

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