Little wonder, then, that the actor is somewhat uncomfortable with his latest role.

Radcliffe has told how his latest part left him feeling compelled to apologise to his co-stars, after racially abusing them on set. Toni Collette, Sam Trammell and Tracey Letts also feature in the cast.

The actor, who plays a white supremacist in new film Imperium, said he would beg forgiveness after difficult scenes, feeling guilty about the words spewing from his character's mouth.

"Whenever I was using racial slurs and stuff in the film I would have to go up to the actors afterwards and be like, 'I'm so sorry'," Radcliffe told US chat show The Daily Show.

"'I know you know that I don't mean this, but I still feel like I have to say it'. We were the most apologetic bunch of skinheads."

The film, due out later this year, tells the story of an FBI agent, played by Radcliffe, who goes undercover to infiltrate a local white supremacist group as they attempt to make a bomb.

The actor said: "It was a very weird film to make in one way because it was a fantastic experience and it was a great crew.

"On the other hand, we are dealing with this very heavy stuff and filming, like, Right-wing, white-supremacist rally scenes and we were all wearing T-shirts that said 'white power' on them, and stuff like that is weird and horrible."

Speaking of how he had to shave his head on camera, in one take, for the role, he joked: "I was happy to find out I don't have a strangely shaped or marked head in any way."

The Telegraph, London