Australian actor Heath Ledger wants to play US President George W Bush on screen, in a bid to challenge his acting abilities.

Ledger insists it is vital for him, as an actor, to understand what drives people - even those he dislikes.

He says, "I could totally identify with George W Bush if I had to.

"I can be sympathetic towards any person and figure them out enough to play them and love them as human beings.

"I know how to breathe and so do they, so that's at least one way I can relate to them."