Medical files purporting to relate to F1 legend Michael Schumacher are being offered for sale, his management team has warned.
Manager Sabine Kehm said it was unclear whether the documents were genuine.
But she said they were “clearly stolen” and warned that criminal charges would be pressed if such “confidential files” were bought or published.
Schumacher, 45, was placed in a coma after a skiing accident in December but has now left hospital.
It is not clear what the alleged medical data might contain or relate to.
However, in a statement Ms Kehm said: “For several days stolen documents and data are being offered for sale. The offerer claims them to be the medical file of Michael Schumacher.
“We cannot judge if these documents are authentic. However, the documents are clearly stolen. The theft has been reported.”
She added: “The contents of any medical files are totally private and confidential and must not be made available to the public.
“We will therefore, in every single case, press for criminal charges and damages against any publication of the content or reference to the medical file.”
Schumacher’s management team announced on 16 June that the F1 champion had left hospital in Grenoble in France and was no longer in a coma.
Schumacher has been transferred to Lausanne university hospital in Switzerland.
The seven-time F1 champion was placed in a medically induced coma after suffering a severe head injury in a skiing accident in the French Alps on 29 December.
His management has tried hard to protect his privacy, saying the rehabilitation would “take place away from the public eye”.
Medical experts say rehabilitation from this sort of injury could take months or years.
Investigators probing the accident said Schumacher had been going at the speed of “a very good skier” at the time of his crash in the resort of Meribel.
He had been skiing off-piste when he fell and hit a rock, investigators said.
Schumacher retired from racing in 2012 after a 19-year career.
He won two titles with Benetton, in 1994 and 1995, before switching to Ferrari in 1996 and going on to win five straight titles from 2000.
