Saoirse Ronan has said that playing the part of two characters in The Host was challenging.

The 18-year-old Irish actress, who plays the part of a girl whose body is taken over from an alien soul, admitted that it was a difficult role to take on.

Speaking to MTV, Saoirse said: ''It was challenging but it was great at the same time because I'm either playing one or I'm playing the other, or I'll switch between the two in one scene.

''So you'll map that out a bit whenever that happens.''

However, Saoirse did explain that she did enjoy taking on the challenge of playing two people living in one body, adding: ''I really liked it because for the majority of the shoot, I was playing Wanda, who's - she's a great character to play, but she's a perfect Soul and doesn't really feel any negative emotions.

''So I could go from playing the perfect being to someone who's a real fighter, who's really kinda gutsy, who has a mouth on her, and it was really nice to be able to do that.''