Phoenix stuns viewers with bizarre behaviour

Joaquin Phoenix has stunned viewers with his bizarre behaviour during an appearance on The David Letterman Show.

The Gladiator actor, who recently quit movies for music, slurred his words and gave only monosyllabic answers throughout an interview to promote upcoming film Two Lovers.

Dressed entirely in black and sporting dark sunglasses, the unkempt star seemed confused as Letterman tried to question him, even appearing to forget the name of his co-star Gwyneth Paltrow.

A visibly frustrated Letterman attempted to lighten the mood by saying, "What can you tell us about your days with the Unabomber?", which prompted peals of laughter from the audience but sparked little response from his guest.

Discussing his decision to take some time off movies, Letterman quipped: "Some believe you're taking a little time off tonight!" A subsequent mention of Phoenix's hip-hop career drew giggles from the crowd but a bemused reaction from the actor, who offered to return to the show and perform.

The chatshow host ended Phoenix's appearance by saying: "Joaquin, I’m sorry you couldn’t be here tonight."

Several reports have suggested that Phoenix's rebirth as a rapper is a hoax, but he has insisted that he is entirely serious in his decision to switch careers.