Sam Claflin struggled to keep a ''straight face'' while filming 'The Quiet Ones'.

The 27-year-old actor - who is best known for his role as Finnick Odair in 'The Hunger Games' - hits the big screen as Brian McNeil in the John Pogue-directed horror and insists it was difficult not to laugh on set where the cast needed to put on ''scared faces''.

Talking to BANG Showbiz at the film's premiere in London yesterday (01.04.14), he said: ''Trying to keep a straight face was so hard. The cast knew each other so well and spent the majority of the filming with our scared faces. We had this amazing director making noises and sound effects, as you can imagine there's no music, no sound effects [while filming], so we were lucky enough to have this amazing man!''

His co-star Jared Harris - whose character Professor Coupland attempts to create a poltergeist - revealed filming was intense because of the short period of time they had to shoot scenes.

He added: ''Shooting a movie in three and a half weeks was tough, we were under a lot of pressure. Luckily we had rehearsals before but it's a tough schedule to stick to.''

They were joined by Olivia Cooke and Rory Fleck-Byrne on the red carpet.