Hollywood filmmaker James Cameron's much anticipated 3-D sci-fi epic Avatar is being touted as the most expensive film ever - with a whopping $230 million (Rs 1,200 crore) budget, according to a company statement.

Releasing on December 18 worldwide, the action-adventure is Cameron's comeback directorial venture after his multiple Oscar-winning Titanic (1997).

Conceived by Cameron 14 years ago, the movie took four years of actual production work and is also generating unprecedented buzz, courtesy the path-breaking technology that has been used for its filming.

Already being praised as a "fully immersive cinematic experience of a new kind" and a "revolutionary technology" that will "alter moviemaking experience" across the globe, Avatar has been shot using the Fusion digital 3-D camera developed by Cameron and Vince Pace.

Produced by Twentieth Century Fox, the motion picture is a blend of live-action photography and virtual photo realistic production techniques.

Starring Sam Worthington, Sigourney Weaver and Zoe Saldana, the movie shows the story of a wounded ex-marine thrust unwillingly into an effort to settle and exploit an exotic planet rich in bio-diversity, who eventually crosses over to lead the indigenous race in a battle for survival.

Advance bookings for the film have already opened in several parts of the US.