Celebrity Gossip's

Sienna Miller has been stripping off to play a hippie - complete with flowers in her hair - in an upcoming role.

The 25-year-old is known for her bohemian fashion sense and it seems that now she is taking that sensibility one step further.

In her role in movie Hippie Hippie Shake, Sienna plays artist Louise Ferrier, the girlfriend of Australian underground magazine editor Richard Neville. Margo Stilley and Cillian Murphy also have parts in the swinging 60s film.

The actress is no stranger to the era, having taken on the role of Andy Warhol's muse Edie Sedgwick in biopic Factory Girl.

According to the Daily Mail, directors of Hippie Hippie Shake have asked Sienna to change her exercise routine so that she can develop a more rounded figure for the role, as well as dying her hair from blonde to brunette.

One insider claims Sienna is 'perfect' for the part: "She is not shy when it comes to stripping off and it is little wonder."

"She has always been praised for her distinctive boho look and even without clothes, she pulls this off."

Sienna is currently still filming the flick in various UK locations. Hippie Hippie Shake has a release date of sometime in 2008, but we'll let you know when they make it official.