Christopher Lloyd would love 'Back To The Future 4' to become a reality.

The 79-year-old actor played time travelling scientist Emmett 'Doc' Brown in the iconic science fiction trilogy, and he has admitted he would be keen to reprise the role if a fourth film was produced.

He told the Phoenix New Times: ''I'd be delighted. I'd love to be in a fourth film, if they could come up with the right idea that extends the story and does it as well as the first three.''

Lloyd - who starred opposite Michael J. Fox in the films - admitted while it was possible, the idea of another sequel relies on director Robert Zemeckis and his co-writer Bob Gale having the passion for it.

He explained: ''Well, I think its a matter of, first of all, it's important if Bob Zemeckis and Bob Gale are excited about doing another episode [of 'Back to the Future'], I think, really, the most important thing is if they can come up with the right idea.

''I think that's the challenge is to come up with something that really is as good as the originals. I suppose it could happen.

''I have not heard that they're looking for that, if they've made up their minds ... hey, here's something we could do, and they believed in it then they might get going to do it.''

Meanwhile, the star also admitted his favourite film in the trilogy was actually the third, which saw Doc and Marty McFly go back in time to the Wild West.

He said: ''I kind of like the last one the best. It was a western, and westerns are always fun. There was a lot of horseback riding; Doc Brown had a romance with the lovely Clara.

''So the third one I think is the most fun. I don't know if anything can top the original.''