The director - who is currently in a Swiss jail facing extradition to the US, from where he fled in 1978 after being convicted of unlawful sex with a minor three decades ago - is reportedly trying to ensure he completes the film in time for the Berlin Film Festival in February.

Novelist Robert Harris - who is collaborating with Oscar winner Roman on the film and wrote the original book and screenplay - said: "I don't think he can make phone calls, but he can communicate".

"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".

"The Ghost" stars Ewan McGregor as a ghostwriter following a British Prime Minister - played by Pierce Brosnan - who begins to suspect that the death of his predecessor was not entirely straightforward.