ALBERTVILLE, FRANCE (REUTERS) - The French mountain slope on which former Formula One champion Michael Schumacher had a skiing accident had been prepared according to national standards, the local prosecutor told a news conference on Wednesday.

"There are French standards setting rules on safety, signalling, demarcation... The checks we have made show these standards had been respected," said prosecutor Patrick Quincy.

He was presenting the results of a police investigation into a Dec 29 fall that left Schumacher in a critical condition with brain injuries. The German has been in an induced coma since then and has undergone two operations in Grenoble.

Quincy added that he could not assess Schumacher's speed at the time of the accident after watching footage from the German's helmet camera.

"I watched the film, the investigators have been watching it too, but it's hard for me to assess the speed," he said.

Schumacher, a seven-time Formula One champion who retired in 2012, was skiing "beyond the marked-out zone", French high mountain gendarmerie officer Stephane Bozon said.

"It is tricky for now to say how fast, in kmh, he was skiing, but it was the pace of a good skier on a slope that is not too steep," he said.

Bozon also ruled out Schumacher's skis playing a part in the accident, saying: "The skis are not the cause of the accident."