Days after illegal immigrant dramas Dirty Pretty Things and In This World won at London's British Independent Film Awards, a film directed by an exile from Afghanistan has triumphed at the London film festival.

Osama, billed as the first film from post-Taliban Afghanistan, won this year's prestigious Sutherland Trophy, which is awarded by festival parent the British Film Institute to the most original and imaginative feature at the event.

Directed by Afghan-born Siddiq Barmak, the film examines the harshness of life under the Taliban through the eyes of a 12 year-old-girl who is forced to disguise herself as a boy in order to earn a living.

Barmak was born in Afghanistan and attended film school in Moscow before being forced to flee Afghanistan in 1996. He lived in exile in Pakistan, returning after the fall of the Taliban.

"Osama is a timely and distinctive piece of film making, bringing a major new talent to the international film making community," said the festival's artistic director, Sandra Hebron. "The film combines skilful storytelling with striking visuals and strong performances throughout, to powerful and moving effect."

The film's UK distributor is ICA Projects, which scored a surprise hit with Kandahar, Mohsen Makhmalbaf's story of life under the Taliban regime.

"We're thrilled to be distributing Siddiq's brilliant and highly topical film - we plan to make it an even bigger success than Kandahar," said Jane Giles, director of ICA Projects.

Earlier this week, Stephen Frears' Dirty Pretty Things, a drama about illegal immigrants working in the UK hotel trade, swept a host of prizes at the BIFAs including best film. Michael Winterbottom's In This World, about two Afghan boys trying to reach London, came away with multiple awards.