Katy Perry gave her fans a bit of a surprise by personally appearing at a special screening of her upcoming 3D film 'Part Of Me'.

The singer was hosting a preview of her new film at a London cinema as the movie's official release date edges nearer.

However, Perry turned up to the screening and sat with her fans, posing for photos and even giving one plucky man in the audience a hug.

She meanwhile posed for photos in the cinema's foyer, holding a box of popcorn and generally looking happy to have made her fans' day.

As previously reported, Katy Perry opened up on the Graham Norton Show recently about her past year, admitting that she had a lot of "tough times" as her marriage dissolved.