Former International Olympic Committee (IOC) president Jacques Rogge, who created the Youth Olympics, has died at the age of 79, the IOC said on Sunday.
No details were given and the IOC said the family has asked that their privacy be respected.
Rogge, a Belgian surgeon, presided over the IOC in succession of Juan Antonio Samaranch from 2001 to 2013, after leading the Belgian Olympic Committee in the past.
He has left behind wife Anne, a son, a daughter and two grandchildren.
Rogge was an Olympic sailor at three Games in 1968, 1972 and 1976 and also a rugby international.
“The entire Olympic Movement will deeply mourn the loss of a great friend and a passionate fan of sports,” IOC president Thomas Bach said.
“First and foremost, Jacques loved sports and being with athletes —- and he transmitted this passion to everyone who knew him. His joy in sports was infectious.
“He was an accomplished president, helping to modernise and transform the IOC.”
Rogge helped restore the image of the IOC battered by the bribery scandal around the awarding of the 2002 Winter Games to Salt Lake City.
He was a staunch fighter against doping and the Youth Olympics which debuted in 2010 for 15- to 18-year-old athletes were his brainchild.
The IOC also achieved United Nations (UN) observer status during his reign.
World Athletics president Sebastian Coe, the chief organiser of the London 2012 Games, said: “I am beyond (being) sad to hear the news of Jacques passing.
“I have a mountainous gratitude for his part in the seamless delivery of London 2012. No Organising Committee could have asked or received more.
“He was passionate about sports and all he achieved in sports and beyond were done with common decency, compassion and a level head. We will all miss him.”
The IOC said its flag at the Lausanne headquarters would be lowered to half-mast and that “a public memorial service will take place later in the year, where members and friends of the Olympic Movement will be able to remember his life and his great contribution to sports.”