Joaquin Phoenix is uncomfortable with the amount of violence in 'Joker'

Joaquin, 45, walked out of an interview in September when asked by a journalist about whether the film would "inspire" violence to consult with Warner Bros as he had not been asked a question relating to the film's violence.

He told the LA Times newspaper: "It was an awkward position to be in because I thought, 'Well, I can't address this because this is the thing that is potentially - that's precisely what you shouldn't do.' So it suddenly seemed like I was being evasive and trying to avoid this topic because it made me uncomfortable. But I was really thinking, 'This is the very thing that would excite this kind of personality."

Director Todd Phillips, 48, believes that the film has been "vindicated" by its reception, despite the questions over its violent nature.

He said: "It's not the box office but the reception that's been vindicating. It's the fact that I get emails from people telling me that the movie made them look at their sister who suffers from schizophrenia in a different light.

"Ultimately, the film is about the power of kindness and the lack of empathy in the world, and the audience seems to have picked up on that. It's amazing that a movie that was supposed to inspire, as they put it, mass mayhem really has just inspired a bunch of people dancing down staircases. I think that speaks more to our times than anything."

Meanwhile, Joaquin also admitted that he didn't expect 'Joker' to be so successful.

He said: "I don't think I expected this movie to be successful. I don't know if I had any expectation. Honestly, Todd and I were just trying to make something that didn't end our careers."