Forest Whitaker breathed a sigh of relief when he learn Desmond Tutu approved of his portrayal of the South African cleric.

The 56-year-old actor plays the iconic religious leader and civil rights activist in the drama film 'The Forgiven', and he's admitted to being delighted by Tutu's reaction to the movie, which also stars Eric Bana.

He confessed: ''I was quite moved because I'd been really scared about it, you know, because he impresses me so much. I was worried that I wouldn't reach what he wanted and his expectations.''

Forest actually got to meet Tutu before he took on the role, and he admitted that proved to be a major help.

Speaking to Entertainment Tonight, the Academy Award-winning actor explained: ''I was trying to understand the man, and I knew his laugh, and I knew his sense of humour, I knew how he felt, his passion, his faith, you know what I mean.

''But trying to capture it by sitting with him. So I sat with him in his home, I sat with him at his offices. We talked quite a bit and it was very helpful to me.''

Despite being one of Hollywood's most acclaimed actors, Forest confessed that playing Tutu proved to be one of the biggest challenges of his career.

Forest - who starred as Ugandan dictator Idi Amin in the 2006 hit 'The Last King of Scotland' - shared: ''It was more difficult to try to find ... to keep the centre of Desmond Tutu.

''The sort of - I don't wanna say calm - but graceful way in which he looks at the world and stuff and still keep the sense of humour that he has. Trying to pull those things together, so you can catch the spirit of the man.''