Ben Affleck chose to cast himself in 'Argo' as well as direct the film because he loved the script so much.

The 40-year-old actor directed the movie and he was keen to star as real-life CIA 'exfiltration' specialist Tony Mendez - who devised a plan to free six Americans in Iran during the 1979 revolution - because the unusual nature of the loosely-based true story appealed to him.

He said: ''I wanted to play him [Tony] because the script was really interesting.

''It struck me, right away, that you had this thriller and then, in equal measure, this comic Hollywood satire and this really intricate real-life CIA spy story based on truth.

''That seemed like a fantastically interesting and unusual movie to be a part of, and I really wanted to direct it.

''And then, the actor side of my brain that's still in that phase of auditioning and trying to make connections and get work asked the director of that movie for a job, and the director was in a tough spot and had to say yes.''

Ben received the script for the film from producer Grant Heslov after he and George Clooney - partners in Smokehouse Pictures - were impressed with the screenplay by Chris Terrio, and Ben was taken aback at just how ''amazing'' it was.

He added to ''When I got the script, I couldn't believe how good it was. They said, 'This is our best script.' And I thought that was some executive hyping me on it, but it really was pretty incredible.

''I was amazed. I talked to Grant and George and said, 'Look, I really want to do this. This is amazing!' And they said, 'Okay, great! Let's do it!'

''So, we took it to Warner Bros. And then, I went back and talked to Chris and said, 'How did you do this?' I looked at some documentaries and read some books and thought, 'God, this is really unwieldy. It felt like it should have been a 10-hour mini-series. How did you get that down into a three-act structure?'''