The surgeon who operated on Alex Zanardi following his accident on Friday evening admits the former F1 driver's condition is not yet clear.

"The condition of Alex Zanardi is serious but stable," said Dr Giuseppe Olivieri, the head of neurosurgery at Siena's Santa Maria alle Scotte hospital, according to Associated Press.

"He arrived here with major facial cranial trauma, a smashed face, and a deeply fractured frontal bone," he continued, referring to the Italian's forehead. "The numbers are good, although it remains a very serious situation.

"We won't see what his neurological state is until he wakes up... if he wakes up," he admitted. "Serious condition means it's a situation when someone could die. Improvement takes time in these cases.

"Turns for the worse can be sudden," he continued. "The operation went according to the plan. It's the initial situation that was very serious.

"The next step is to try and stabilise him over the next week or 10 days. Then if things go well, he could eventually be woken up and re-evaluated.

"As I told his wife, he's a patient who is worth being treated. As far as a prognosis of how he'll be tomorrow, in a week or in fifteen days, I don't know. But I'm convinced that he should be treated."

"The situation is clearly critical in terms of brain damage," admitted Sabino Scolletta, the director of the hospital's intensive care unit.

An official statement issued by the hospital at 11:30 (10:30 BST) today (Sunday) reads: "Regarding the clinical conditions of Alex Zanardi, the Health Department informs that the patient spent the night in conditions of cardio-respiratory and metabolic stability.

"Organ functions are adequate. He is sedated, intubated and mechanically ventilated.

"The ongoing neuro-monitoring has shown some stability but this data must be taken with caution because the neurological picture remains serious.

"The current conditions of general stability still do not allow to exclude the possibility of adverse events and, therefore, the patient always remains in a reserved prognosis."