Those closest to Michael Schumacher have defended the family's decision to refuse to divulge information about the F1 legend's health status.

Schumacher, the seven time world champion, turns 50 on Thursday amid almost complete secrecy about the extent of brain injuries he sustained in a 2013 skiing fall.

On the occasion of his birthday, the great German's wife Corinna issued a statement saying Schumacher is "in the very best of hands".

"We are doing everything humanly possible to help him. Please understand that we are following Michael's wishes and keeping such a sensitive subject as health, as it has always been, in privacy," the statement added.

Those closest to Schumacher, including his friend and former Ferrari boss Jean Todt, backed that stance.

When asked by La Gazzetta dello Sport to reveal whether Schumacher is cognitively able to follow a formula one race, the Frenchman replied: "Here I stop."

In Welt newspaper, Todt admitted that despite remaining close friends with Schumacher and his family including monthly visits, "we no longer have the same communication as before".

But on the specifics of Schumacher's condition, Todt told La Gazzetta dello Sport: "I don't think there's a reason to revisit this point.

"You know that he had this terrible accident five years ago, he's fighting and will continue to do so, he has a team close to him, his family, which is extraordinary," Todt added.

"The rest is private, and it is right that it remains that way."

Another close former Schumacher colleague, F1 sporting boss Ross Brawn, agrees.

"I am constantly in touch with Corinna, and I totally agree with their decision," the former Ferrari technical boss said.

"It's completely understandable that Corinna has wanted to maintain the same approach to Michael's privacy, which was a guiding principle in his career.

"Even after the tragic event, it's a decision we must all respect," Brawn added.

And Luca di Montezemolo, the former Ferrari president, said he too is "in contact with Corinna, but I share the family's decision to keep Michael's life private.

"We all have to respect his privacy," he told Il Fatto Quotidiano.

As for Schumacher's health condition, di Montezemolo told Rai radio: "I hope something (positive) can happen, but I do not want to say anything else except that Michael is fighting with so much determination and with a magnificent family around him."