Keira Knightley was in a constant ''bad f***ing mood'' when making 'Anna Karenina'.

The 27-year-old actress admits the emotional demands of playing the title role in the new movie - which is based on Leo Tolstoy's classic novel - took their toll on her emotionally and she found it tough to shrug off the character when filming finished each day.

She said: ''I don't think I was the easiest to live with. It was quite a relief to finish - the level of emotion which had to be kept up with was quite exhausting, so the character did come home more than I would have liked her to. I'd just be in a bad f***ing mood.''

Despite her emotional attachment to the role, Keira - who got engaged to Klaxons star James Righton earlier this year - insists she didn't find it too difficult playing someone ''miserable'' when she was so happy in her personal life.

Asked if it was strange playing a character moving away from marriage when she had just taken steps towards tying the knot, she told Britain's OK! magazine: ''No, because I didn't realise at that point that I was. You can be in a happy place and play an incredibly miserable character and vice versa.''

Keira's working commitments mean she hasn't started planning her wedding yet but is looking to do so early next year.

She said: ''I'm working on another film which finishes after Christmas.

''Then maybe I'll start thinking about the dress and the guests and the venue.''