Clean-shaven Joaquin Phoenix apologises on David Letterman show

Actor Joaquin Phoenix has returned to David Letterman's TV talk show to apologise for his controversial appearance last year that turned out to be an elaborate piece of performance art.

"You've interviewed many, many people and I assumed that you would know the difference between a character and a real person, so ... I apologise," Phoenix said. "I hope I didn't offend you in any way."

No offence taken, Letterman replied, adding that the chance to lob jokes at Phoenix was fun.

Phoenix was clean-cut and shaven on The Late Show last night, without the shaggy beard, unruly hair and sunglasses he wore on February 11, 2009, when he told the befuddled Letterman that he was giving up acting for a rap career. Describing that appearance yesterday, Letterman said it was "like you slipped and hit your head in the tub".

Instead, Phoenix was playing a role for film-maker friend Casey Affleck. The fake documentary on Phoenix's "career change" - I'm Still Here - is currently out in cinemas.

At Letterman's urging, Phoenix made clear that the talk show host was not in on the joke.

"We'd hoped to come on a talk show," Phoenix said with a laugh, "and I was looking for a beat down, and I got one ... I want to thank you for that."

Phoenix, who said the experience of making the movie was "really gratifying", revealed that Affleck was angry with him for briefly taking off his sunglasses at the end of the appearance as he was shaking Letterman's hand.

"I was eager to thank you for the opportunity and I was really eager to get off the show," he said.

Affleck, who appeared with Jay Leno on the Tonight show on Tuesday, said no one from Hollywood called to express concern about Phoenix when he was acting strangely.

"Afterward, the movie comes out, the critics like to say, 'This is crazy, this is disturbing, this is sick'," he said. "But while it's happening, people were happy just to mock him and make fun of him."

Letterman, who became a key part of the movie, said: "Somehow I get the sense that I had been made fun of," and demanded a million dollars for his role in the ruse.

"We've made 75 cents on this movie," Phoenix protested.

"That's not my problem," Letterman said.

Phoenix promised to "work it out" and asked to talk about it privately.

"We'll go to one of your screenings," Letterman shot back.