Joaquin Phoenix's spokesperson has hit out at rumours that the wannabe rapper has schizophrenia.

The former actor's recent dishevelled appearance and bizarre behaviour has sparked rumours he is suffering from mental illness.

Psychiatrist Paul Dobransky told MTV News that he believes the star's behaviour and appearance point to the symptoms most commonly associated with schizophrenia.

But Joaquin's rep has rubbished the claims, saying: "How absolutely inappropriate for a doctor who has no personal interaction or relationship with someone to diagnose them."

Joaquin recently shocked audiences in America with an odd, distracted interview on David Letterman.

It has been suggested that the Oscar-nominated actor's career change is a hoax concocted by himself and brother-in-law Casey Affleck, who is filming his assault on the music industry.