Michael Schumcher's manager Sabine Kehm lashed out at experts who she claimed were "upsetting" the stricken racer's family by speculating about his condition.

Kehm also turned her fire on media reports about claims made by medical experts who have no direct involvement in Schumacher's treatment.

Speaking out in a rare interview to a German TV station, Kehm said: "What upsets the family most is media quoting doctors who are not treating Michael and untruths are constructed from these.

"It has been a problem when outsiders comment and it means we have to set the record straight, even when we don't want to."

Her intervention follows a slew of reports by doctors about Schumacher's prospects for recovery. Last month, Formula One's former chief medic Gary Hartstein warned fans to prepare for "really bad news" and claimed the racing driver had been a victim of "mismanagement" by staff at Grenoble University Hospital. Hartstein admitted that he was not involved in treating the seven-time F1 champion.

Kehm has been with Schumacher's wife Corinna and other relations in a round-the-clock vigil at the 45-year-old's bedside.

In comments which will boost hopes of fans praying for Schumacher to beat his catastrophic ski crash injuries, Kehm suggested he was able to interact with his surroundings.

"There are short moments of consciousness and he is showing small signs of progress," she said. "There are moments when he is awake and moments when he is conscious.

"Of course I am not a doctor, but medically, there is a distinction between being awake and being conscious, the latter meaning there is an ability to interact with his surroundings.

"I don't want to disclose details out of respect for the family, but we have no doubt at all in the abilities of the doctors treating Michael, they are experts in their field."

Kehm's encouraging comments support earlier reports by her about how Schumacher was progressing since falling in to a coma more than three months ago. Earlier this month, she revealed he was experiencing "moments of consciousness and awakening."