Director, who is currently working on two screenplays, says some of the profits from his sci-fi sequels will go to green causes

Avatar parts two and three will be shot back to back and released in December 2014 and 2015 respectively, director James Cameron has revealed.

In an interview with Entertainment Weekly at the Producers Guild awards in Los Angeles at the weekend the film-maker said he was currently hard at work on the screenplays for the two features. He revealed that a certain amount of the profits from the series would go to environmental causes.

"I am in the process of writing the next two Avatar films now," said Cameron. "We are planning to shoot them together and post them together, and we will probably release them not quite back to back, but about a year apart. Christmas '14 and '15 is the current plan."

The film-maker has previously hinted that the second film might take place on another planet in the same solar system as Pandora, the fertile forest moon upon which Avatar's action took place. He has also mentioned the possibility of exploring the planet's oceans. Cameron was staying tight-lipped about further details at the weekend but revealed that characters which survived the first film "get to be in the second film, at least in some form".

Of the donation to green causes, the film-maker said: "Fox has partnered with me to donate a chunk of the profits to environmental causes that are at the heart of the Avatar world. I didn't want to make more Avatar movies without a grander plan in place."

Given that the first film made more than $1bn across the globe and stands as the highest-grossing movie of all time, proceeds could be substantial. As yet no announcement has yet been made about how the sequels, which will mark Cameron's first venture into trilogy territory, might be titled.