Hein Verbruggen, former president of the International Cycling Union (UCI) and one of the most prominent sports administrators of his time, has died. He was 75.

The Dutchman, head of the UCI between 1991 and 2005, was heavily implicated in the doping scandals that rocked elite cycling when he ran the sport.

Most notable in that era was the case of American Lance Armstrong, who defeated cancer to go on and win seven straight Tour de France races from 1999 to 2005. Armstrong was stripped of his titles in 2012 and banned from the sport for life. The fallen US cycling hero later admitted taking banned substances. (Keep up with the biggest news in cycling by subscribing to our newsletter!)

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Verbruggen, also a member of the International Olympic Committee between 1996-2005 and again from 2006-8, was accused by an independent commission in 2015 of attempting to shield Armstrong from investigation.

The Cycling Independent Reform Commission (CIRC), set up following allegations of corruption at the heart of the UCI, said the body "exempted Armstrong from rules, failed to target test him despite the suspicions, and publicly supported him against allegations of doping, even as late as 2012".

The commission said "requesting and accepting donations from Lance Armstrong, given the suspicions, left UCI open to criticism".

Travis Tygart, the head of the US Anti-Doping Agency (USADA), even called for the prosecution of Verbruggen and Pat McQuaid, UCI president from 2005-13, over the alleged cover-up.

The independent commission later cleared Verbruggen of corruption, the Dutchman insisting that claims that he failed to do enough to combat doping were unfair.

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The IOC, in a statement Wednesday, dubbed Verbruggen, who also headed the SportAccord Convention of international sports federations from 2003 to 2013, "a cycling fanatic and a true sports fan."

"Hein Verbruggen was a fearless fighter for his sport. Thanks to his great engagement and his management skills, he greatly contributed to the success of the Olympic Games Beijing 2008 as chair of the coordination commission. For this he will be always remembered," said IOC president Thomas Bach.

The IOC said that as a mark of respect, the Olympic flag will be flown at half-mast at its headquarters in Lausanne.