Former Formula One champion Niki Lauda. File picture: Heinz-Peter Bader / Reuters.

Zurich - Former Formula One champion Niki Lauda is in hospital in Vienna with the flu, five months after undergoing a lung transplant, Austrian media sites reported on Sunday.

Lauda, 69, an Austrian, was flown in early January from the Spanish island of Ibiza where he had been vacationing to a hospital in the Austrian capital, the publication Oesterreich reported on its website.

Oesterreich reported that Lauda was in the intensive care station but should be released from the hospital later this week, without citing sources.

A spokesperson at the Vienna General Hospital could not immediately be reached for comment.

Lauda, who was badly burned in 1976 in a Formula One race and later became an airline entrepreneur, underwent a lung transplant in August and was recuperating from the complicated surgery. 

Lauda later said that undergoing a lung transplant had been worse than his horrific crash at the German Grand Prix in 1976, which left him with severe burns.

"When I had the accident in Germany it was only a matter of a month or so, I had burns, I was burnt, but I left it quickly. Now it was really long, but I'm still here ...," Lauda said in an interview with Gazzetta Dello Sport.

The Austrian underwent surgery in Austria last August, and left hospital two months later.

"I knew it would be hard, very hard," he said. "In such conditions I could only do one thing: fight.

"I was never afraid. I was in the hands of specialists.

"I did it for every moment, I'm still doing it."

Lauda was given the last rites after his crash only to return to the cockpit later that season after missing just three grand prix.

Since then he has suffered from the after-effects of the toxic gases he inhaled in the accident and also required kidney transplants in 1997 and 2005.

Reuters & Agence France-Presse