Mila Kunis has defended Natalie Portman's dancing in 'Black Swan'.

The 27-year-old actress - who appeared alongside the Oscar-winning star in the ballet-based thriller - has hit back at claims Natalie's body double Sarah Lane performed "90 per cent" of the intricate moves used in the movie, saying the brunette beauty "danced her a*s off".

Mila explained: "Natalie danced her a*s off. I think it's unfortunate that this is coming out and taking attention away from the praise Natalie deserved and got.

"She'll tell you that, no, she was not on pointe when she did a fouette turn. No one is going to deny that. But she did do every ounce of every one of her dances."

The 'Forgetting Sarah Marshall' star admitted while every member of the 'Black Swan' cast had a dancing double at their disposal, they were only used as a "safety net".

Speaking to Entertainment Weekly, Mila added: "Her dancing double wasn't used for everything. It was more like a safety net. If Nat wasn't able to do something, you'd have a safety net.

"The same thing that I had - I had a double as a safety net. We all did. No one ever denied it."

Natalie won the Best Actress Oscar for her depiction of ballet dancer Nina Sayers in 'Black Swan'.