Australian cricketer Phil Hughes has died surrounded by his family and close friends, the Australian Team Doctor has confirmed.

Hughes had been in an induced coma in a Sydney Hospital after being stuck in the head by a bouncer while playing for South Australia against New South Wales at the SCG on Tuesday.

Australian Cricket team doctor Peter Brukner says he passed away a short time ago. He was 25-years-old.

"He was not in pain before he passed and was surrounded by his family and close friends," says Mr Brukner.

"As a cricket community we mourn his loss and extend our deepest sympathies to Phillip's family and friends at this incredibly sad time."

Mr Bunker says he had never regained consciousness following Tuesday's incident.

The Australian flag has been lowered to half-mast at Cricket NSW headquarters.

Earlier today, radio host Allan Jones, revealed the seriousness of the head injury.

Jones, on his 2GB radio show, told listeners that Hughes suffered damage to a "major artery in the back of his head."

"That caused bleeding over the skull and prevented blood going to the brain, and I'm advised neurology is very, very bad or language that the layman understands the brain is very sick," Mr Jones said.

"So this is much more serious than anyone imagined. Medical technology is currently breathing for him. The brain is very sick and we pray for miracles."