Michael Schumacher has reportedly been admitted to a hospital in Paris for "secret treatment”.
The former Formula One world champion was taken to the Pompidou hospital in the French capital on Monday afternoon, Le Parisien newspaper reported.
He has not been seen in public since a skiing accident in the French Alps five years ago. The accident left Schumacher, who turned 50 on January 3, with severe head injuries and in a medically-induced coma for several months.
The French newspaper said the former champion would undergo treatment based on stem-cell transfusion by French surgeon Philippe Menasche.
It did not cite its source of information in the report.
A spokeswoman for Schumacher did not immediately return a request for comment.
The German remains motor racing's most successful driver, with a record 91 grand prix wins.
He won his first two titles with Benetton in 1994 and 1995 before five in a row with Ferrari between 2000-2004.
In January his family released a statement saying he was in "the very best of hands".
