Rita Ora has been cast as Mia, Christian Grey’s adopted sister, in the film version of EL James's best-selling erotic novel, Fifty Shades of Grey.(Reuters)
Rita Ora has been cast as Mia, Christian Grey’s adopted sister, in the film version of EL James\'s best-selling erotic novel, Fifty Shades of Grey.(Reuters)

She is preparing to make her big screen debut in the Fifty Shades of Grey film, but pop star Rita Ora has admitted that her foray into acting has not been easy.

The RIP songstress, who plays Christian Grey's sister Mia Grey in the movie adaption of EL James's bondage trilogy, has revealed that she got so nervous when filming scenes that she kept forgetting her lines.

As a result of her anxiety getting the better of her, film bosses had to arrange for somebody to feed her lines through an earpiece.

"I had to have someone in my ear on set telling me what to say before I said it because I was honestly like so nervous I forgot everything that I had learnt."

Ora credits her friend and co-star Dakota Johnson, who plays Anastasia Steele in the film, for helping her feel more comfortable on set.

"She's [Dakota is] a great friend of mine and she really eased me, and she was really nice to take care of me."

While some fans complained that the recently released trailer is boring and expressed their disappointment over the casting of Jamie Dornan as Christian Grey, Ora insists that they could soon be eating their words.

She said: "The movie is as visually close as it can be [to the book]. I think the actors are phenomenal in this and I'm just kind of honoured to be on the same wavelength as them.

"This being my first movie, it's pretty awesome."

Fifty Shades of Grey will be released on 14 February 2015.