Cinderella actress Lily James has dismissed criticisms her waist has been made to appear too thin in the Disney remake as "irrelevant".

The fairytale film has proved a box office hit in the United States - but it has faced a backlash from parents claiming Cinderella has an unnaturally small waist.

Lily James, 25, reportedly had to go on a liquid diet to fit in to the tight-fitting corset for the role.

Questioned over criticisms of the waistline at a press conference ahead of the film's UK premiere, James said: "Why on earth are we focusing on something so irrelevant?"

Sandy Powell, the film's costume designer, told reporters at London's Claridges Hotel that she does not understand all the fuss about Cinderella's waist.

She said: "I don't understand what the concerns are actually.

"Lily does have a small waist, but then so do all the other girls in the film, all the girls in the film wear corsets because that's what you wear with period clothes - it creates the silhouettes."

She added: "Lily's dress in particular is an optical illusion, I have to say. The diameter of the skirt is about two metres and it has the width and that really does make the waist smaller than it actually is."

The film's producer Allison Shearmur also stepped in to rebuff accusations it gave an unrealistic portrayal of a woman's body.

The American said: "I'm a mum and I'm one of the producers of the film, and I think it's gotten a lot of attention, but the funny thing is it's kind of paying attention to the opposite of the theme of the movie - which is your sense of beauty and your strength is what's on the inside.

"Sandy is right, I was there for all the early fittings - I would look like I had a two inch waist. There is giant set of shoulders and butterflies and it was customary for women to be corseted at the time.

"Not only is it an optical illusion but I think it is interesting that the conversation has been about the outside, because this is a movie where the real emphasis is on the inside.

"My 12 year-old daughter thought the dress was really pretty, but what she took away from the film was the priority of courage and kindness."