Sienna Miller has signed to star in the movie version of G.I. Joe.

The 25-year-old star of “Alfie” and “Factory Girl” will play the “sexy femme fatale” female lead.

The new movie is set in Brussels and revolves around an international force of operatives who use high-tech equipment to fight Cobra, an evil organisation headed by a Scottish arms dealer.

The movie is directed by The Mummy’s Stephen Sommers and is scheduled for release in August 2009.