IOC President Thomas Bach says former IAAF head Lamine Diack brought his sport "into the abyss" by extorting money from athletes to cover up doping.
In a broad-ranging interview with German sports magazine Kicker, Bach said track and field's world governing body faces a "rocky road" in its attempt to clean up the sport, but that the new IAAF president, Sebastian Coe, has taken the right initial steps.
The IAAF has been deeply shaken by allegations of state-sponsored doping in Russia and deep-rooted corruption at the heart of the federation and centred on Diack, who is facing criminal corruption charges in France.
"It is really incomprehensible that the president of an international federation demands money from athletes to manipulate results of doping tests," Back was quoted as telling Kicker in its Monday edition. "That is really a look into the abyss."
Bach's interview coincided with reports that German sportswear company Adidas may terminate its sponsorship deal with IAAF because of the corruption and doping scandals. Adidas said only that it is in "close contact with IAAF to learn more about their reform process."
Diack, who stepped down as IAAF president last August after 16 years in charge, is a former IOC member. He resigned as an honorary member in November, a day after he was provisionally suspended by the IOC executive board.
Bach said the IAAF under Coe had sent the right signals by suspending the Russian federation, getting in touch with the World Anti-Doping Agency and forming a commission to initiate reforms.
"These were the right and important measures. It is also true that, as Sebastian Coe has said, the IAAF faces a rocky road ahead because of the scale of the problem," Bach said.
The suspension of the Russian federation means its athletes may not be able to compete at the Olympics in Rio de Janeiro in August.
Bach said the IOC's "zero tolerance" anti-doping policy meant that every athlete, coach, doctor or official involved must be punished, but that "clean athletes have to be protected."
Bach said the newly elected leadership of the Russian athletics federation is "a strong signal" of Russia's readiness to step up the cleaning up process.
"The IAAF now has to see what progress has been made and if or when that suspension can be lifted," Bach said.