British actor Benedict Cumberbatch considered pulling out of his role in the upcoming WikiLeaks film after receiving a 10-page email from Julian Assange urging him not to make the movie.
The Star Trek Into Darkness actor plays Assange in new film The Fifth Estate, which tells the story of the Australian journalist and the whistleblowing website he founded.
However, Cumberbatch nearly walked away from the project after he was contacted by the man he was to portray just a day before the shoot was due to begin.
Cumberbatch reveals Assange wrote a "very considered, thorough, charming and intelligent account of why he thought this was morally wrong for me to be part of something he thought was going to be damaging in real terms - not just to perceptions but to the reality of the outcome for himself".
The actor spoke about the email with Britain's The Guardian newspaper, admitting he considered quitting the film after reading the email.
"The fact that it was coming from the man himself, the day before we started filming? Of course I would hear and feel the protests of the man I was about to pretend to be. I'm a human being ...
"He (Assange) characterised himself as a political refugee, and with ... other supporters of WikiLeaks who have been detained or might be awaiting detention, and the organisation itself - all of that being under threat if I took part in this film."
Cumberbatch says he spent hours struggling to compose a reply after he decided to keep his job.
"I said (in my response) 'Listen, this film is going to explore what you achieved, what brought you to the world's attention, in a way that I think is nothing but positive. I admit to doing work because I'm a vain actor ... yet I'm not acting in a moral vacuum. I have considered this, and whatever happens I want to give as much complexity and understanding of you as I can'."
Assange has been living in the Ecuadorean embassy in London since 2012 as he battles extradition to Sweden, where he is wanted over allegations of sexual assault.
He fears it will pave the way for his transfer to the US over his website, which he used to publish thousands of classified military documents.
The Fifth Estate is due for release in Australia in November.