Kathryn Bigelow has become the first woman to win the best directing Oscar, as her Iraq war drama The Hurt Locker took six prizes, including best film.

"It's the moment of a lifetime," said Bigelow - only the fifth woman to be nominated in Academy Awards history.

Jeff Bridges and Sandra Bullock won the top acting Oscars for their roles in Crazy Heart and The Blind Side.

Christoph Waltz and Mo'Nique were the winners of the supporting acting awards, categories they were both widely tipped to win.

Waltz won for his role as a diabolical SS officer in Inglourious Basterds, while Mo'Nique triumphed for her role in Precious. "I would like to thank the Academy for showing that it can be about the performance and not the politics," said the 42-year-old comedian. Precious also picked up the best adapted screenplay award for screenwriter Geoffrey Fletcher.

James Cameron's 3D sci-fi juggernaut Avatar left with just three technical awards - for art direction, cinematography and visual effects.

Argentina's The Secret In Their Eyes pulled off a surprise win for foreign-language film over higher-profile entries that included Austrian Cannes winner The White Ribbon and French prison drama A Prophet.

Critically acclaimed 3D film Up, also shortlisted in the best picture category, won best animated feature film.