Natalie Portman's fiancé has jumped to her defence following revelations that the actress used body doubles for scenes during her Oscar-winning Black Swan performance .

Benjamin Millepied - who choreographed and acted as her dance partner in the film - said of the performance: "It was so believable, it was fantastic."

"There are articles now talking about her dance double that are making it sound like [her body double] did a lot of the work.

"But really, she just did the footwork... and one diagonal phrase in the studio."

He added: "Honestly, 85 per cent of that movie is Natalie."

The 29-year-old actress - who is pregnant with her first child - underwent five-hour-a-day training sessions for a year before filming.

Photo: © Rex