Knightley on 'positive' new role

Keira Knightley has said her latest film role is the most upbeat character she's ever tackled.

The Atonement star plays Penny, a twenty-something undergoing a crisis in Seeking A Friend For The End Of The World.

She explained: "I think she's one of the most positive characters I've ever played.

"She's certainly at a time in her life when everything is changing and she doesn't know who she's meant to be or who she's meant to be with, which I think is a place that a lot of people in their mid to late 20s find themselves, and it just so happens that the world is ending, and she still doesn't know where she's meant to be, or who she's meant to be with."

The film sees Penny break up with her boyfriend, played by Adam Brody, and venture on a road trip with Steve Carell's character, Dodge, shortly before the world is due to end.

"It's sort of about what becomes important, and that's love, and friendship, and companionship and the wonderful moments in life."

Keira, 27, recently announced her engagement to Klaxons rocker James Righton after just over a year of dating.