James Cameron has signed up to direct two 'Avatar' sequels due for December 2014 and December 2015.

The 56-year-old director has confirmed the two movies as his next projects and will begin working on scripts for them early next year.

Cameron confirmed the creation of the movies - which are expected to feature Sam Worthington and Zoe Saldana - would be an "epic Journey" and he said he was hoping to "exceed" the audience's expectation.

He said: "With two new films on the drawing boards, my company and I are embarking on an epic journey with our partners at Twentieth Century Fox. Our goal is to meet and exceed the global audience's expectations for the richness of 'Avatar's' visual world and the power of the storytelling."

He also confirmed the movies would be "self-contained" and "continue to explore themes and characters".

Fox Filmed Entertainment Chairmen Jim Gianopulos and Tim Rothman confirmed the news, claiming it was a "high priority" for the studio.

In a statement, the pair said: "'Avatar' is not only the highest grossing movie of all time, it is a created universe based on the singular imagination and daring of James Cameron, who also raised the consciousness of people worldwide to some of the greatest issues facing our planet.

"We had no higher priority, and can feel no greater joy, than enabling Jim to continue and expand his vision of the world of 'Avatar'. This is a great day in the history of our company."