Prosecutors investigating Michael Schumacher's skiing accident have examined footage from a helmet he was wearing at the time.

Albertville prosecutor Patrick Quincy said film from the helmet camera was very clear and would be examined by experts in mountaineering.

Investigators also said they had established that signage on the slopes was in accordance with regulations, but the area where Schumacher fell was "virgin territory" so was not marked.

Schumacher was skiing in the French resort Meribel when he fell and struck his head on a rock. The fall left him in a critical condition and he has been in a medically induced coma since December 29th.

On Monday, a source close to the retired Formula 1 driver said he had made a "slight improvement" but remained in a stable but critical condition.

There was initially speculation that Schumacher was travelling up to 100kph (60mph) when he crashed, after it was revealed his helmet had split on impact.

But subsequent reports suggested he was travelling at a "leisurely pace" of up to 20kph (12mph).

A camera reportedly attached to Schumacher's helmet is being examined in the hope it will reveal more about the circumstances of his accident.

Schumacher, known affectionately as 'Schumi' by fans, is the most successful F1 driver in history, racking up a record 91 race wins.