Michael Schumacher has shown "slight improvement" after a surgical procedure but is not out of danger, doctors have said.

The  intervention took around two hours, and the coming hours are 'critical' according to medical staff.

Michael Schumacher's family are keeping a bedside vigil at the hospital where he is fighting for his life, as footage emerged of him being airlifted from the scene of the accident.

The Formula One world champion is in an induced coma and medics have warned it is touch-and-go after he fell while skiing in the French Alps.

Schumacher, 44, has undergone brain surgery at a hospital in the southeastern city of Grenoble.

He had been skiing with his 14-year-old son on Sunday morning in the resort of Meribel when he hit the right side of his head on a rock.

The German racing legend was wearing a helmet when he fell

The helmet he was wearing saved his life, but it was not enough to prevent serious head injuries.

At a news conference on Monday morning, doctors said he had suffered many lesions to his brain and that the situation was "extremely serious".

Surgeons operated to remove a blood clot in his brain and have been trying to reduce "dangerous swelling", meaning his condition could go either way.

"He's in a critical situation," Chief Anaesthetist Jean-Francois Payen told journalists.

The chalet reportedly owned by Schumacher in Meribel

The doctor said Schumacher's family were at his bedside and friends had flown in to the hospital to lend their support.

Fans of the German motor racing legend have also been gathering outside. One told reporters: "I came straight away. I had to come."

Doctors are expected to give a further news conference at the hospital at midday.

The seven-time world champion first retired from Formula One in 2006.

He has been hurt seriously once before, in a motorcycling accident in February 2009 when he suffered neck and spine injuries.

Schumacher recovered sufficiently from those injuries to make a comeback to Formula One in 2010.