Dominic Cooper on 'difficult' role of Saddam's son
The Mama Mia star has a dual role in the film, playing both Uday Hussein and Latif Yahia - a man who was forced to be his body double.
The film, directed by Lee Tamahori, finished shooting in Malta last month.
"It's quite a horrible part," admitted Cooper, who was speaking at this week's National Movie Awards.
"It was a difficult challenge, trying to understand who this guy was and why he did such unbelievably terrible things, and then to play this innocent guy who he forced at gunpoint to be his body double."
The film is based on Latif Yahia's biographical novel of the same name. Yahia was made to undergo plastic surgery to his teeth and chin to make him look more like Uday.
When the Gulf War started in 1991, he was sent out to the front line in order to give the impression that Uday was with the troops.
Cooper said of his role: "I do have to wear some prosthetics to change my face."
The film also stars French actress Ludivine Sagnier as Sarrab, Uday's concubine.
Tamahori's past projects include his Maori story Once Were Warriors (1994) and James Bond film Die Another Day (2002).