James Cameron has had enough of talking about money.

The Canadian director's latest movie Avatar, which hits theatres worldwide on Friday, is one of the most expensive films ever made, and media attention has inevitably focused on its performance at the box office.

Asked in an interview to promote the computer-generated 3D spectacular how he felt about reports of costs running as high as $400 million, the 55-year-old replied: Just round it off to an even billion, shall we, and let's put paid to this.

A spokesman for 20th Century Fox which backed it said Avatar cost $237 million to make and $150 million to market.

The picture is seen as a major risk for the studio, a unit of News Corp, given that unlike many blockbusters the story has no built-in fan base from books or other source material.

Cameron, whose Titanic is the highest-grossing film of all time, said the studio should take more credit than him for backing the movie.

The thing is, people have to remember that the studio has to put the money into the film, he said recently in London.

The film evolved over a period of years because it had a lot of aspects of an animated film and they were seeing cuts and so on as we went along and they believed in the film.

If they didn't believe in the film they wouldn't have spent the money and they knew going in that this was going to be a very expensive film but they always believed in it, they always backed my play.

I think that it's fine to say the filmmaker is brave and taking the risk, but the filmmaker's not the one writing the check, you know.

DODGING THE BULLET

Cameron admitted to nerves at last week's premiere of the film, the first time he had seen it with a full audience.

But then when I saw how the normally reserved British press responded to the movie with huge waves of cheering toward the end, I thought, 'Oh I might have dodged a bullet on this one'.

He also said he avoided the worst of the fallout from the financial crisis, with the money largely in place by the time the credit crunch hit.

It was really getting access to capital that was an issue, (and) the capital had already been committed.

So then it was just an issue of is there an economy there where people still want to go see movies? And fortunately what we've seen is that movies have remained one of the few entertainments that haven't taken a huge beating.

Further boosting Avatar's prospects, Cameron argued, was the fact that it was a 3D spectacular less vulnerable to piracy.

You can pirate a 3D movie, but you can't pirate it in 3D, so you can't bottle that 3D experience and do a bootleg distribution of it right now, you've got to go to a movie theater.

So this was a way to sort of get people back to the cinema for the big show, for the big experience and of course Avatar is a big event movie, it was planned that way.

Avatar, which has had generally positive early reviews, follows a crippled ex-Marine who is chosen to make contact with the forest-dwelling Na'vi who are fighting for survival against a mining operation bent on stripping their planet.

It combines dazzling visual effects with the more familiar movie mix of romance, action and battles between good and evil.