The actress plays the feline femme fatale in The Dark Knight Rises and is the first woman villain in Christopher Nolan's Batman trilogy.

She told The Sun: "I didn't realise I was the first -- and I feel a little nauseous. That's a lot of pressure."

Hathaway had little idea of the physical demands of her Catwoman performance, which will highlight her own kick-boxing and mixed martial arts skills.

She said: "I'd always thought I was pretty healthy and I always thought I had worked hard in the gym.

"It turns out that what I thought was hard, in Catwoman's world is actually light to moderate.

She added: "So I've had to ratchet everything up. But I have the most incredible stuntwoman in the world and she's got me and the character to another level. I do all sorts of kicks. I do a roundhouse kick, and I think it's all mixed martial arts. And I've been doing it in heels!"

The intense pressure of looking good for the role was increased because the film uses special IMAX cameras which produce images of extraordinary clarity and vividness.