Keri Russell thinks Andy Serkis is an ''unbelievable'' actor.

'The Americans' star, who takes on the role of Ellie in 'Dawn of the Planet of the Apes', claims her co-star - who provides the voice for ape leader Caesar in the film as well as that of Golum in 'The Hobbit' and 'The Lord of the Rings' movies - isn't given enough recognition in the film industry.

She told The Hollywood Reporter: ''Andy is just so good. That was really the treat of doing this movie. I really hope people start paying attention to him. He's unbelievable.''

Serkis' character leads a nation of genetically evolved apes as they are threatened by a band of human survivors of a devastating virus which was unleashed a decade earlier, and the film's screenwriters claim it was his talent that allowed Caesar to speak.

Rick Jaff and Amanda Silver explained: ''The decision to have him speak and have words - it was really Andy, [We] credit him with figuring out Caesar's voice.''

'Dawn of the Planet of the Apes' is scheduled for release in the UK on July 17 2014.