Los Angeles - James Cameron is being sued by a science fiction writer who claims the director stole his idea for Avatar.
Bryant Moore is seeking $2.5bn from the Academy Award-winning director and 20th Century Fox claiming that James based the 2009 movie on his screenplays Aquatica and Descendants: The Pollination.
James' attorney Bert Fields has slammed the lawsuit, telling The Wrap: "Mr Cameron was demonstrably the author of Avatar. We can prove that, and we intend to prove that in court."
He added that any claim alleging that someone other than the director had authored the movie was "entirely without merit".
A spokesperson for Fox called the suit "baseless", and added "we look forward to vigorously defending our position".
Moore - who cites numerous similarities between the projects including the appearance of mist in a scene - is seeking $1.5bn in actual damages, and $1bn in punitive damages.
He claims other likenesses between the projects include bioluminescent flora/plant life, unbreathable atmospheres, spiritual connections to environment and reincarnation and blue and green skin on the characters.
This is the second lawsuit this month against James, with Eric Ryder claiming the movie was largely lifted from his story idea, "and liberally and substantially uses material" that fell under his agreement with the director's production company, Lightstorm Entertainment.