The family of Heath Ledger, the Australian actor who died seven months ago from a drugs overdose, made an emotional journey to New York for the premiere of The Dark Knight, the latest in the Batman series and the last film he completed.

At the world opening last night, his co-stars queued up to pay tribute and said Ledger should win an Academy Award as best supporting actor.

Ledger is now widely tipped to win a posthumous Oscar for his role as The Joker.

Ledger’s family - his father Kim, sister Kate and mother Sally Bell and stepmother Ines - all attended the New York opening along with his long-time ex-girlfriend actress Naomi Watts.

Family union: Heath Ledger's father Kim Ledger arrived with his wife Ines for the world premiere of Heath's final completed movie Batman: The Dark Knight in New York

His father described the experience as 'bittersweet.' 

Heath Ledger as the Joker in The Dark Knight. The actor is predicted to be in line for an Oscar for his stunning performance

Actress Michelle Williams, the mother of his daughter Matilda, had announced before the screening that she would not be attending.

Mr Ledger signalled his approval for the film and his son’s performance by giving a thumbs-up as he left the cinema.

Ledger died on 22 January in his Manhattan apartment at the age of 28 from an apparent accidental overdose of prescription drugs.

He had been nominated for an Oscar for his performance as a gay cowboy in the 2005 Ang Lee film Brokeback Mountain.

At the premiere in Lincoln Square, Sir Michael Caine led the tributes to his performance.

Sir Michael, 75, who plays butler Alfred Pennyworth in the film, noted the 'intensity and ferocity of the performance'.

'But when we were sitting down between takes, he was completely ordinary,' Caine added.

Heath Ledger's sister Kate attended the star-studded event in tribute to her late brother

Actor Christian Bale and his wife Sibi Blazic arrived in matching black outfits. Bale, who plays Batman, paid compliments to Ledger saying 'working with him was fantastic'

'He wasn’t preparing himself or saying "Please leave me alone, I’ve gotta do this".

'We would sit and chat and have a cup of coffee, then suddenly they’d say, "We’re ready, Heath," and he’d go straight into The Joker.

'His energy was astonishing, he’s certainly the best villain I’ve ever seen.'

Michael Caine, who plays butler Alfred in the film, attended the event with his wife Shakira

Maggie Gyllenhaal, sister of Jake Gyllenhaal, looked stunning in a black floral evening gown as she arrived on the black carpet

Caine added: 'My favourite part is the opening monologue of Heath Ledger as The Joker, it’s one of the best close-ups I’ve ever seen in my life.

'He was a young actor and this is his moment. He did Brokeback Mountain which was fine and he never got the Oscar. He’s going to get the Oscar for this.'

Christian Bale, who plays Batman in the Christopher Nolan-directed film, said: 'Working with Heath was fantastic. He steals the movie and I’m quite happy to say that.

'He’s a hell of a talent and created a Joker that’s very iconic and one that will become a classic portrayal of the ages.'

 Actresses Blake Lively and Lauren Conrad at the premiere

Co-star Aaron Eckhart said: 'I’m especially happy for Heath, and sad he’s not with us tonight. But we’re going to honour him in this movie. He’s huge.'

Maggie Gyllenhaal, the sister of Jake Gyllenhaal, who starred opposite Ledger in Brokeback Mountain and was godfather to his daughter, said: 'He’s so good in the movie, really remarkable. But even before this movie he really had an effect on people.’

The stunning Batmobile was put on display for fans and passerd-bys