Michael Fassbender found it difficult to play a computer with emotions in Prometheus.

The X-Men: First Class actor portrays a leading role in the Ridley Scott-directed movie - alongside Charlize Theron and Noomi Rapace - and admits it is hard to play an "advanced" version of a human in the movie.

"He's hyper-intelligent. His physicality is more advanced than human beings. So, people don't really embrace him. He's sort of used and abused. How does that make him feel, if robots can feel? You're essentially trying to build a computer that has a physicality to it, that can respond and understand human behavior. It's programmed to be able to incorporate itself within a human environment. I just try and explore what's happening within the scene, moment to moment," he said.

Despite playing an android, he admits he wanted to make sure it still had human characteristics. Writer Damon Lindelof admits he wanted the character to seem like a "killer" iPhone app: "I remember a conversation that Ridley and I had, fairly early on, about David. There was this idea that David is mass-produced. There are 20,000 other David units out there, who look exactly like Michael Fassbender. What a wonderful world that would be, wouldn't it? It's the idea that we all have our iPhones, yet we put different cases on them and different apps on them. That's where I felt like, as soon as we cast Michael, that's the killer app, right there. It's pretty cool."