Australia batsman Phillip Hughes has passed away two days after being struck on the head by a bouncer.

Hughes, who would have turned 26 on Sunday, has died of the injuries he sustained while batting for South Australia against New South Wales at the Sydney Cricket Ground.

"It is my sad duty to inform you that a short time ago Phillip Hughes passed away," said a statement from Australian team doctor Peter Brukner.

Hughes, who was wearing a protective helmet, collapsed face first onto the pitch after being hit by a ball on the back, lower left side of his head from pace bowler Sean Abbott as he attempted a pull shot.

He was then given mouth-to-mouth resuscitation and oxygen on the boundary line after being carried off the pitch on a stretcher.

Hughes was then rushed to the city's St Vincent's Hospital, where he underwent surgery and was being monitored in the intensive care unit.

Updates from Cricket Australia yesterday said Hughes remained in a critical condition after undergoing scans but the governing body today confirmed the worst.

Brukner added: " He never regained consciousness following his injury on Tuesday.

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

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

"Cricket Australia kindly asks that the privacy of the Hughes family, players and staff be respected."

Hughes' plight on Tuesday provoked shock in the cricketing world, with many past and present professionals, fans and and governing bodies alike sending messages of support to Hughes.

And news of his death has prompted a mournful reaction, with Australia coach Darren Lehmann leading the early tributes on Twitter.

"RIP you little champ, we are all going to miss you ! Love, prayers to all the Hughes family xxxx," he wrote.

Pakistan and New Zealand confirmed that a minute's silence would be observed before they began day two of their Test match in Sharjah in memory of Hughes.

Following the incident, the match between New South Wales and South Australia was called off for the day before being abandoned entirely, while the latest round of Sheffield Shield games followed suit yesterday.

Hughes - well-known to English fans both internationally and domestically after spells with Hampshire, Middlesex and Worcestershire - had been visited by several Australia team-mates.

Australia captain Michael Clarke, a close friend of Hughes, was said to be one of the first to visit St Vincent's Hospital and comfort the player's mother and sister, who were reportedly watching the game in the stands.

An injury to Clarke had led to talk of Hughes getting a recall for the the first Test against India, which is slated to begin next week in Brisbane but may now be in doubt of going ahead.

A 26-Test international, his last appearance for Australia came in a one-day international against Pakistan in October.

Hughes memorably scored two hundreds in just his second Test match against South Africa, with his last five-day appearance coming against England at Lord's last summer.

In the Test prior to that he scored 81 at Trent Bridge alongside Ashton Agar in a last-wicket stand that nearly produced a memorable win.

Nathan Lyon and Steve Smith paid tribute to their former Australia team-mate, whose doctors did not give details on the extent of Hughes' injuries.

"Today we lost one of the greats! RIP Hughes #408 #willbemissed #loveyamate," wrote spinner Lyon.

Smith added: "Rest in peace Hughesy. I am really going to miss you. You were 1 of the great blokes and I will never forget you. #408 will live on forever."

Former paceman Brett Lee, who also played alongside Hughes in the national team, tweeted a picture of him sat alongside the batsman and said: "No words can describe the loss Rip."

South Australia chief executive Keith Bradshaw said Hughes was a "very popular member" of the dressing room and "loved by everyone" in Adelaide.

"While everyone at SACA is hurting, the immediate thoughts of all staff and players are for Phillip's family who were with him at St Vincent's Hospital in Sydney," he said in a statement.

"He was a very popular member of both the West End Redbacks and Adelaide Strikers cricket teams and a favourite of the SACA members and cricket fans across South Australia and Australia, and we are all struggling to come to terms with the news," Mr Bradshaw said.

"Loved by everyone, Phillip was a really terrific person and a remarkable talent. He had many friends and team-mates here and interstate that will need support, and it is important we offer them our love and care as we all come to terms with this tragic event.

"The out-pouring of support for Phillip over the past few days has been overwhelming, and a testament to how much of an impact he had on so many people."

The England team released a statement on Twitter, saying: " Our deepest sympathies go out to Phil Hughes' family, friends and teammates at this incredibly sad time.

"Phil was admired and respected by all he played with and against and will never be forgotten by the cricket community."