Revenge of the Sith will be Lucas' sixth Star Wars film

"It's a real tearjerker, and it will be received in a way that none of us can expect," he told an audience at the ShoWest convention in Las Vegas.

Lucas said he was not concerned at how fans would react to the final film.

"I feel that I've made the movie the best I can and it turned out the way I wanted it to be, so I'm happy."

Episode I - The Phantom Menace and Episode II: Attack of the Clones both received mixed reviews but were still phenomenally successful at the box office.

Obviously, fans would love to see a movie about Darth Vader running around killing people George Lucas

"I never try to anticipate what the world's going to think or even worry about whether they're going to like it or not," Lucas told the convention of cinema owners.

"That's not my job, to make people like my movies. They either like them or they don't. That's completely out of my hands."

The audience at ShoWest was treated to the opening six minutes of the film.

The new film, Revenge of the Sith, will be released on 19 May

They saw Jedi Knight Anakin Skywalker, played by Hayden Christensen and master Obi-Wan Kenobe, played by Ewan McGregor, engaged in a space battle.

Lucas has already warned that the action scenes are probably too violent for young audiences.

While keeping the plot firmly under wraps, Lucas said: "Obviously, fans would love to see a movie about Darth Vader running around killing people."

"I'm not telling that story, and I'm not interested in that. That's not what the movie is.

"This first trilogy is really about the father, the struggles of a father, or a man, basically, to find himself, and at the same time fall into a trap of wanting certain powers, making a pact with the devil and basically spending the rest of his life regretting it."