Natalie Portman won a Best Actress Oscar last night for her role as a ballet dancer in Black Swan.

The 29-year-old played Nina Sayers in the psychological thriller, which saw her character striving for perfection.

The film also features an explicit lesbian sex scene between Portman and her co-star Mila Kunis, who plays a ballet rival.

Portman, who is pregnant with her first child, thanked her fiance Benjamin Millipied for his support.

She said: “Thank you to my beautiful love Benjamin Millepied who choreographed the film and has now given me my most important role of my life.”

The star joked that she would not call her unborn child Oscar.

Last night’s overall winner was The Kings Speech, starring Colin Firth.

The film won Best Picture, Best Actor, Best Screenplay and Best Director.

The Social Network won Best Adapted Picture, while Christian Bale and Melissa Leo won supporting acting awards for boxing drama The Fighter.