The 40-year-old, who will replace injured Felipe Massa in the Ferrari team for the European Grand Prix in Valencia, Spain, on August 23, and possibly for the rest of the season, injured his neck in a motorcycle accident last February.

But Kehm insisted that the injury could hamper his return.

"He's still not absolutely certain that his neck will hold up.

"His return depends on medical examinations which have yet to take place. Only after these tests will it be clear if he can drive," Kehm told German agency SID.

She added: "Michael is commited 100 per cent to his return and is completely immersed in preparations for the Valencia meeting.

"It all depends on his health and the doctors' opinion."

Schumacher admitted on Tuesday that his neck was still bothering him.

"... all in all, training is going pretty well. I only have to admit that my neck pinches a bit," he said on his website.

"We have to get a grip on that as health has priority - that's the clear arrangement made with Ferrari and, by the way, with my wife, too," added the German, who retired in 2006.

Source:  supersport.co.za