Tributes have poured in for Formula One world champion Niki Lauda who has died at the age of 70.
The former racing driver "passed away peacefully", his family said in a statement reported by the Austria Press Agency.
A tweet from British racing driver Jenson Button said: "A legend has left us. Rest in peace Niki."
His family added in their statement: "His unique successes as a sportsman and entrepreneur are and remain unforgettable.
"His tireless drive, his straightforwardness and his courage remain an example and standard for us all.
"Away from the public gaze, he was a loving and caring husband, father and grandfather. We will miss him very much."
Lauda was also mourned by F1, who tweeted: "Forever carried in our hearts, forever immortalised in our history.
"The motorsport community today mourns the devastating loss of a true legend."
The McLaren Formula One team said: "All at McLaren are deeply saddened to learn that our friend, colleague and 1984 Formula 1 World Champion, Niki Lauda, has passed away.
"Niki will forever be in our hearts and enshrined in our history."
Mercedes tweeted a photograph of Lauda smiling with a love heart emoji and the words "Niki, 1949 - 2019".
Lauda narrowly escaped death in 1976 when his Ferrari crashed at the Nurburgring in Germany.
He made a miraculous recovery despite horrific burns and finished second in the championship to James Hunt.
The rivalry between the pair was later made into a film starring Daniel Bruhl as Lauda and Chris Hemsworth as Hunt in 2013.
Lauda went on to win two of his three titles as well as becoming a prominent figure in the aviation industry.
In 1979 he left the sport to concentrate on setting up his airline, Lauda Air.
He briefly returned to racing following an offer from McLaren, winning the F1 drivers' championship for a third time in 1984, before retiring for good the following year.
Lauda founded a new airline, Niki, in 2003.
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In later years, he served as the non-executive chairman of the Mercedes team and formed a close bond with driver Lewis Hamilton, who joined the team in 2013.
Over the past few decades, Lauda twice underwent kidney transplants, receiving an organ donated by his brother in 1997 and a kidney donated by his girlfriend in 2005.
In August last year, he underwent a lung transplant that the Vienna General Hospital said was made necessary by a "serious lung illness."
He was released for rehabilitation nearly four months later but was back in hospital in January with influenza.
The doctor that performed the transplant, Walter Klepetko, confirmed his death early on Tuesday morning, the Associated Press reported.
Lauda is survived by his second wife Birgit, and his children, Max, Mia, Mathias, Lukas and Christoph.
