Lorraine Kelly is known for her fits of giggles and it was obviously catching when she interviewed Sienna Miller and Keira Knightley.

The actresses appeared on the LK Today show to promote their movie Edge of Love, about the life of Welsh poet Dylan Thomas.

In the film the British stars play love rivals who become friends.

Their friendship has obviously spilled over into real life as the pair spent most of the time giggling with each other.

Hysterics: Sienna Miller and Keira Knightley laughing and joking as they speak to Lorraine Kelly during a live link

Hug: The actresses look like the best of friends

There was no glimpse of any off-screen rivalry as they hunched together in laughter and Sienna gave Keira a sisterly hug.

The pair said they knew each other before making the film but had not worked with each other before.

In the film, written by her mother, award-winning playwright Sharman Macdonald, Keira sings a number of songs including Blue Tahitian Moon.

Giggles: the girls are unable to answer a question from presenter Lorraine Kelly

Asked whether she did her own singing in the film, Keira, 23, replied: 'Yes, it was the most terrifying thing I have done in my entire life.

'My knees actually nearly buckled, I was so nervous,' she added on the GMTV programme.

The film will have its premiere at the Edinburgh film festival on Wednesday.