Sienna Miller is to play the female lead in the film of GI Joe.

She will play a sexy baroness-cum-spy in the movie based on the soldier toy.

Work on the live-action film is due to start in February, reports Variety.com.

Miller is the first member of the cast to be confirmed for GI Joe, which is scheduled to hit cinemas in August, 2009.

The plot sees a high-tech international team of agents combating a Scottish arms dealer.

Source: Press Release