Charlize Theron is not certain to return to the 'Mad Max' franchise.

The Oscar-winning actress starred as Imperator Furiosa alongside Tom Hardy in the critically-acclaimed action movie 'Mad Max: Fury Road' earlier this year, but director George Miller has confessed he doesn't know if Charlize will reprise the role for the sequel.

Asked about the possibility, the 70-year-old film-maker said: ''I'm not sure, is the answer.

''She's not in the 'Mad Max' [sequel] story, but in one of the stories there's an interaction between [Max and Furiosa]. I can't really say more than that because it's still in progress.''

What's more, George confirmed that the previously-mentioned sequel name, 'Mad Max: The Wasteland', is not sure to be the film's final title.

He told Digital Spy: ''That name came out, that was just a working title.

''[Screenwriter] Nico Lathouris and I wrote deep backstories on all the characters and they eventually became screenplays - so we have two [more movies].

''I'm happy to say that there's discussions about them right now, but I hope the next film I make is a very small without any special effects and not many stunts.''

'Mad Max: Fury Road' is the highest grossing film in the history of the franchise, having made $374 million worldwide.