Niki Lauda's doctor has played down rumours the Mercedes team chairman is back in a life-threatening situation with pneumonia.

Earlier, it emerged that while on holiday with his family in the wake of his 2018 lung transplant, the F1 legend had to fly back to Austria to be treated for influenza A.

It was confirmed that Lauda, 69, was back in intensive care, but Welt newspaper and other publications said the Mercedes team chairman had developed pneumonia.

Lauda's treating doctor Walter Klepetko told Kurier newspaper that the great Austrian is "very tired", explaining that it is "not a classic infection" and "more than a cold".

"Because of the transplant, the situation is more complex than with a healthy person," he added.

But Osterreich newspaper insisted that Lauda is not in a life-threatening situation and is still scheduled to leave the hospital sometime next week.

Klepetko said Lauda could not be treated on a "normal ward" due to his transplant, but he is already able to get out of bed.

"Niki was looking after his health and doing everything right," he added. "In his situation, certain risks are inevitable."

Klepetko explained that Lauda does not have pneumonia, is not ordered to stay in bed, and does not need to be ventilated.