The Titanic moviemaker has spent two years in pre-production as he readies three follow-ups to his blockbuster 2009 sci-fi epic, but he has now revealed the preparations are nearly finished.

Cameron hopes to move forward with filming after Christmas (15), telling, "We have design more or less finished, which is an enormous task. It's been about a two-year task. (We've finished) all the creatures and the landscapes, and the new worlds within the world of Pandora that you see.

"The writing is ongoing, but almost finished. Technical development is done. Stages are done. Infrastructure. So we're really poised to start after the first of the year."

The director had hoped to release the first film in the new trilogy next year (16), but it is now expected at the end of 2017.

"Christmas of '17 is the target... At least, that's what we've announced," he adds. "But I don't consider that to be as important as the fact that when we get all three films done, we drop them a year apart. I call it a meta-narrative that runs across the three movies. Each film stands alone, but it also tells one much larger story."

Avatar won three Oscars and became the highest-grossing film ever with worldwide box office takings of almost $3 billion (£1.9 billion).