Schumacher was critically injured on December 29 after a skiing accident at the French ski resort Meribel.
Schumacher has remained unconscious since 29 December and fans should prepare for 'really bad news', Dr Hartstein has warned Reuters

Comatose motor racing star Michael Schumacher has been the victim of "serious lapses in judgment" by medical experts treating him for devastating ski crash injuries, a top F1 doctor has claimed.

Former chief doctor of Formula One, Gary Hartstein said he had been told by "usually impeccable sources" that "medical misjudgments" have contributed to the seven-time F1 champion's plight.

Writing on his blog, Hartstein warned fans of the German racer to prepare for some "really bad news". It was, he said, becoming "less and less likely that Michael will emerge to any significant extent".

He alleged lapses in the care of Schumacher from when he was airlifted off a mountain in the skiing resort of Meribel to Grenoble University Hospital but did not go into detail. Hartstein said: "I think that serious lapses in judgment were evident during Michael's initial management [which] almost certainly did worsen the outcome in Michael's case."

Hartstein, the American former chief doctor of Formula One, spent years at race tracks with Schumacher as part of the medical team.

He speculated that Schumacher had remained at Grenoble instead of being transferred to a different hospital because of experts' guilt.

He said: "It is possible that the staff at Grenoble feel duty-bound to not place any pressure on the family to transfer out, despite the terribly dismal prognosis."

Schumacher has been unconscious in the hospital since suffering catastrophic injuries while skiing in Meribel with his son and a friend in December. Such a long time unconscious undermined hopes of a meaningful recovery, Hartstein warned. The racer was in a "persistent coma" he said.

"A vegetative state is defined as persistent when it lasts two months after the precipitating event. As we've mentioned previously, the longer one remains in a vegetative state, the less the likelihood of emerging."

"I spent years at circuits drenched in red by the Ferrari caps, flags, and shirts, and all of that for Michael. I'm still staggered by the depth and persistence of his fans' love for him," he continued on his blog.

"And whereas I worried more than a bit about what was going to happen when and if really bad news got announced, I've realised that perhaps the lack of status updates has given us all a chance to move on a bit, to process what's happening, and to start to detach."

Schumacher's family have remained defiantly upbeat about the champion's prospects and have clung to claims of small signs of recovery. Their hope contrasts with recent reports stating doctors have told them Schumacher "needs a miracle."

The German is one of the all-time great racers, with seven Formula One titles to his name, including five in a row he won at Ferrari from 2000.

Ferrari president Luca Cordeo di Montezemolo recently said: "Michael at the moment needs that affection and support from everyone."