Former Hollywood actor Joaquin Phoenix's attempts to launch a rap career are part of an elaborate hoax for a new art project, sources have claimed.

Phoenix performed three songs apparently from a forthcoming hip-hop album at a club in Las Vegas earlier this month.

But the show, which was filmed by Phoenix's brother-in-law, director Casey Affleck, ended chaotically when the rapper fell from the stage.

The fall, and Affleck's involvement at the gig, prompted speculation about the seriousness of Phoenix's new project.

Now one source close to Phoenix claims the two-time Oscar nominee said his shambolic performance was part of “a put-on”.

“I'm going to pretend to have a meltdown and change careers, and Casey is going to film it,” Phoenix apparently said before the show.

Meanwhile, another unnamed associate told EW: "It's an art project for him. He's going full out. He probably has told his reps that he's quit acting.

“Joaquin is very smart. This is very conscious. He has a huge degree of control."

Phoenix has insisted that his career move is genuine, and that he is enjoying having the “chance to do something straight from the heart and put it out there.”

Phoenix has stood down from his acting career twice before, although never with such a definite ending.

(by Jason Gregory)