Tom Hanks has joked he is easy to spot in new fantasy epic Cloud Atlas because of the shape of his head.

The film is set over six different timelines spanning 500 years, and Tom plays numerous roles, including a doctor in the South Pacific in 1849, a nuclear power plant worker in 1970s San Francisco and a goatherd in 2321.

He said: "I think of all the actors in the film, I'm the most recognisable in all six incarnations, because you can't change the shape of this head!

"The great thing about this is that we get to put on clothes and pretend to be different people we're not. It was liberating fun every time."

But the Oscar-winning actor admitted even he had his doubts that David Mitchell's notoriously complicated best-selling novel could be made into a movie.

"A lot of the time, screenplays speak for themselves but [with this one] I actually said, 'You sure you can get the financing to make this?'"

But he insists writer-directors Lana and Andy Wachowski - the sibling team behind The Matrix trilogy - and German-born director Tom Tykwer have pulled off something incredible.

"Do you remember that period of time when every movie had explosions and some guy running away from it? It doesn't mean anything any more," insisted Tom.

"That's all secondary to the mind games the film's playing. I don't think anyone's going to say you've got to see this because of the special effects."

:: Cloud Atlas is released in cinemas on Friday, February 22