British film The King's Speech has been crowned best picture at the Oscars, with star Colin Firth named best actor, BBC reports.

Tom Hooper was named best director for the film, which also won for best original screenplay at the ceremony.

Its best picture rival, The Social Network, won for adapted screenplay, film editing and score. Natalie Portman won best actress for Black Swan.

Briton Christian Bale and Melissa Leo won supporting acting awards for boxing drama The Fighter.

Firth, who had been firm favourite to win for his portrayal of King George VI battling a stammer, joked: "I have a feeling my career's just peaked."

The success of The King's Speech denied director David Fincher and his film The Social Network, the story of the creation of Facebook that was considered its closest rival at the ceremony in Los Angeles' Kodak Theatre.

Paying tribute to his film's stars, Hooper said: "Thank you to my wonderful actors, the triangle of man-love which is Colin Firth, Geoffrey Rush and me. I'm only here because of you guys."

Screenwriter David Seidler thanked the Queen for "not putting me in the Tower of London" for the swearing that featured in his Oscar-winning script.