Heath Ledger's last film will go ahead with Johnny Depp, Colin Farrell and Jude Law as the late actor's replacements, director Terry Gilliam has confirmed.

The Brokeback Mountain star was working on fantasy adventure The Imaginarium Of Doctor Parnassus when he died of an accidental overdose in January.

Gilliam said in a statement: "I am grateful to Johnny, Colin and Jude for coming on board and to everyone else who has made it possible for us to finish the film. I am delighted that Heath's brilliant performance can be shared with the world.

"We are looking forward to finishing the movie and, through the film, with a modicum of humility, being able to touch people's hearts and souls as Heath was able to do."

It had been suggested that Ledger's role would be completed using CGI (computer generated imagery) special effects, as happened when Oliver Reed died during the making of Gladiator.

But the film's producers said: "Since the format of the story allows for the preservation of his entire performance, at no point will Heath's work be modified or altered through the use of digital technology. Each of the parts played by Johnny, Colin and Jude is representative of the many aspects of the character that Heath was playing."

The project is going ahead with the blessing and support of Ledger's family, the producers added.

Filming has resumed in Vancouver, Canada, and the movie is likely to be released early next year.

Ledger was found dead in his New York apartment on January 22 after taking an accidental overdose of prescription drugs.

Three days earlier he had filmed scenes for The Imaginarium of Doctor Parnassus in London. He left a two-year-old daughter, Matilda, by former partner Michelle Williams.