The head of the International Olympic Committee says he feels an "inner rage" at evidence of state-sponsored doping cover-ups in Russia.
Thomas Bach says the second part of an independent report answers important questions left from its initial work in July.
After revealing his "inner rage" about the scandal in the interview with German newspaper Frankfurter Allgemeine Zeitung, he said: "But neither anger nor fear are good advisers. Therefore one in responsible position has to ask straight away, how do you deal with this? What can you do to ensure that it hopefully never happens again?"
The IOC decided not to ban the country from the summer Games in Rio, despite the findings presented by Professor Richard McLaren.
It has now emerged that more than 1,000 Russian athletes benefited from cheating in sport, including at London 2012.
International Association of Athletics Federations president (IAAF) Sebastian Coe, who was chairman of the London 2012 Organising Committee, also spoke of his anger this week regarding the scandal.
He said: "I was angry (when I heard) because every athlete that was in that stadium had devoted half of their young lives to that moment.
"To have that dream, that ambition, that decade of hard work, the commitment of family and friends and massive financial sacrifice ripped asunder in such a shoddy way made me feel angry."
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