The father of stricken Formula 1 driver Jules Bianchi has admitted that he feels "less optimistic" over his son's health nine months after he crashed at the Japanese Grand Prix.

The 25-year-old, who suffered serious brain injuries after colliding with a recovery vehicle at Suzuka, remains in a coma at a hospital in Nice.

"It's unbearable, it's a daily torture," Philippe Bianchi said in an interview with France Info radio station. "We sometimes feel like we're going crazy because for me, it certainly is more terrible than if he had died. For we're not able to help him more than we can.

"Time goes by and I am now less optimistic than I may have been two or three months after the crash, when we could hope for a better evolution. At some point, you need to be well-grounded and realise how serious the situation is."

Bianchi's father also added that his son would "not at all" want "huge disabilities" if he ever awakes from the coma.

The driver was competing for Marussia at the time of the crash.