Avatar 2 has been delayed a year and will not be released until 2017, director James Cameron has revealed.

James Cameron said he is working on three new Avatar films at the same time.

Avatar 2 was supposed to be out in December 2016, but James Cameron said writing the stories had become “very involved”.

“There’s a layer of complexity in getting the story to work as a saga across three films,” he explained.

James Cameron said the goal was to have the scripts for the three movies completed by the end of this month so that filming can begin.

“We’re writing three simultaneously and we’ve done that so that everything tracks throughout the three films,” he told the Associated Press.

“We’re not just going to do one and then make up another one and another one after that.

“And parallel with that, we’re doing all the design. So we’ve designed all the creatures and the environments.”

James Cameron, 60, said he thought it was important that each film linked forward to the next one in a satisfying way, but also came to a resolution that did not leave the audience hanging.

The three films will be shot in New Zealand, where some of the original film was also made.

Avatar is the highest-grossing film in history, with box office takings of almost $2.8 billion.