As head of media operations, Edgar was responsible for managing the delivery of media facilities and services at the Olympic Games.

He worked closely with Olympic Organising Committees, National Olympic Committees, International Federations and major news organisations such as the Associated Press, Reuters, Agence France-Presse, Xinhua and publications such as Sports Illustrated and The New York Times.

Edgar was also chairman of the IOC Press Committee.

"After 18 years I am leaving the IOC, taking the opportunity of an early retirement to return to Sydney to spend time with my ailing father and my children," Edgar wrote in a Facebook post.

Following the 1996 Olympics in Atlanta, which he covered as a journalist/photographer for a sports magazine, Edgar was offered the opportunity to join the Sydney 2000 sports department, responsible for sport content and publications for the Olympics and Paralympics.

"I had to pinch myself," he wrote.

"For a lover of the Olympic Games, I thought all my dreams had come true.

"This was surely the best gig in the world - the responsibility of interviewing, writing and photographing the greatest athletes in the world, Olympians past and present, for the greatest show on earth."

In 2001, the International Volleyball Federation invited Edgar to join them as press chief, which brought him to Switzerland.

Two years later, he said he was in the "right place at the right time" for Gilbert Felli, the veteran former IOC Olympic Games executive director, to offer him the position of IOC head of media operations for the Olympics.

"Athens 2004 was 12 months away and Torino 2006 was around the next corner," Edgar wrote.

"Beijing 2008 - the biggest event ever - was to be all consuming.

"It was also a time of transition - Jacques Rogge had started his IOC Presidency, the Olympic Games Department had just been established, Gilbert had been appointed the first Olympic Games executive director, and the IOC had decided to take over full responsibility for Olympic Broadcasting Services with Manolo Romero appointed chief executive."

Facebook, Twitter and the iPhone were each launched over the next 40 months of Edgar starting at the IOC, ushering in a new social, digital and mobile future.

He described how this triggered tumultuous change globally and turned the media landscape upside down, impacting how sport would be consumed, broadcast and reported on in the future.

"To have been in a leadership position during these turbulent times and to work hand-in-hand with the international news agencies and news networks to navigate a course forward will stay as one of my fondest of memories," Edgar wrote.

Edgar gave a special mention to his bosses and mentors such as Felli, Romero, Kevan Gosper, the ex-first vice-president of the IOC and chairman of the IOC Press Commission - now known as the Press Committee - for 25 years, and Tom Curley, the former President of The Associated Press.

"Each one a visionary, all strong individuals, and each of them passionate about the Olympic Games," he wrote.

"They understood the need for media freedom and the importance of an independent press. 

"Each of them has helped strengthen the all-important relationship between sport and the media."

Gosper is among those to have paid tribute to Edgar, saying: "Anthony's contribution to the International Olympic Committee's standing with international news agencies and media organisations cannot be overstated.

"He was the 'go-to' person for the top echelon of global media management across all regions of the sporting world for new ideas and innovative solution in showcasing the competitive magic, excitement and drama that only the Olympic Games can deliver. 

"He was always on the lookout for new and improving ways for journalists, photographers and television news producers to report on the Olympic Games and inspire their various audiences.

"Over the many years he worked with me in my role as chair of the IOC Press Commission and vice-chairman of the Beijing 2008 Coordination Commission, I greatly valued his constructive advice, his willingness to explore new ideas, his energy, his integrity and especially his loyalty. 

"He has become a highly-valued friend and I wish him well in his new ventures."

Curley added: "Anthony had a significant impact on the Olympic Movement by helping global news agencies and other media organisations open doors to new forms of coverage and extend the impact of the Olympics to millions of new followers.

"We also salute and thank Anthony for a spirited defense of human rights issues, including press access, gender equality as well as his forceful advocacy for the highest professional standards."