"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.

The Hurt Locker and Avatar led the nominations on Sunday, with nine nominations each, but James Cameron's 3D sci-fi juggernaut left with just three technical awards - for art direction, cinematography and visual effects.

The Hurt Locker's screenwriter Mark Boal heralded the film's first success of the night, winning best original screenplay. Technical awards followed in film editing, sound editing and sound mixing.

The low-budget film has made just $15m (£9.9m) at the box office, becoming the lowest-grossing film to win the best picture Oscar.

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 France's A Prophet.

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

The animation also picked up the Oscar for best original score, for Michael Giacchino, who urged other would-be film-makers to "get out there and do it - it's not a waste of time".

Former Oscar winner Nick Park missed out on the award for best short animated film - for the Wallace and Gromit film A Matter of Loaf and Death - losing to French film Logorama.

However, costume designer Sandy Powell became the first British winner of the night, winning her third Oscar for her work on The Young Victoria.