Three-time Formula 1 World Champion Niki Lauda has undergone surgery in Austria and is currently recovering from a lung transplant.
Lauda has been absent from recent races and no official reason had been given, other than recent media reports which suggested he had a mild illness.
However the hospital treating him released a statement on Thursday confirming the seriousness of his surgery and reported it had been a success.
"Due to a severe affection of the lungs, Niki Lauda had to undergo a lung transplantation at the AKH Vienna today," read the statement.
"The transplantation was done successfully by Walter Klepetko, head of thoracic surgery, and Konrad Hotzenecker.
"We kindly ask for your understanding that the family won't give any official statements and we ask to protect the privacy of the Lauda family."
Lauda, who recently sold his airline Laudamotion to Ryanair, is currently non-executive chairman and a shareholder in the Mercedes AMG F1 Team.
