The film, directed by Briton Christopher Nolan and co-written by him and his brother Jonathan, cost $200million to make.

Dan Fellman, head of distribution at Warner Bros, attributed the film's success to the 'unique vision' of Christopher Nolan and the 'outstanding' performance of Australian actor Ledger in what turned out to be his last completed screen role.

The 28-year-old, who died of an accidental overdose of prescription drugs in January, will be honoured in the end credits of the film.

His co-stars, including Michael Caine, have said that he deserves an Oscar nomination.
He said: “I just watched him and talked to him for three days and I thought he was extraordinary.”