The Hobbit films could be extended to a trilogy, according to film industry reports.
Discussions are taking place between director Peter Jackson and Warner Brothers.
Additional filming is thought to be needed if the Lord of the Rings prequel is stretched to a three-parter.
The first instalment is due out on 14 December and the follow-up on 13 December 2013.
The three Lord of the Rings films, which came out between 2001 to 2003, made a combined total of nearly $3 billion at the box office and The Hobbit movies are thought likely to repeat that level of success.