The participation of Russian track and field athletes in the Olympic Games is in doubt following a raft of allegations against sportsmen and women representing one of the powerhouses of international sport.
In an exclusive interview with CNN's Amanda Davies, Bach said he had not spoken to the Russian President Vladimir Putin despite a fresh raft of accusations from a former head of the country's anti-doping laboratory.
And the IOC chief promised his organization would come down hard on athletes and nations found guilty of doping.
"What has to be done, and this is what the IOC is initiating immediately is a fully-fledged inquiry into everything and then based on these facts we will take our decisions," said Bach.
"And these decisions will be about zero tolerance."
Russia's track and field team were banned from global competition following revelations of "state-run doping" from the World Anti-Doping Agency's independent commission back in November.
The athletics team still faces potential exclusion from the Rio 2016 Games, with the International Association of Athletics Federations (IAAF) council set to rule on its fate at a meeting on June 17.
It has also emerged that the FBI and federal prosecutors are investigating the allegations of widespread doping by Russian athletes, according to a U.S. law enforcement official.
The Kremlin responded angrily to reports of that probe, with spokesman Dmitry Peskov telling Russian media Wednesday that U.S. justice does not apply outside of its jurisdiction.
Often described as the most powerful man in world sport as the head of the Olympic movement, Bach insisted there had been no contact with Putin despite recent allegations that Russian officials had cheated the doping system at the Sochi 2014 Winter Games.
Bach said there had been no discussions with the Kremlin, insisting "President Putin is a head of state with whom we have working relations like with more than 100 heads of state all over the world."
The IOC chief insisted WADA would play a key role in the organization's "fully-fledged inquiry."
Asked by CNN whether the IOC was passing the buck, Bach replied: "No. WADA has all the means in hand. They have the scientific background. They are responsible for the accreditation of the laboratories.
"It's the WADA standards for ther laboratories which are affected. They have their own intelligence unit in their house with an officer who will chair this inquiry."
The former head of the Moscow anti-doping laboratory, Dr Grigory Rodchenkov, had claimed in the New York Times that he developed a three-drug cocktail for Russian competitors in Sochi, and also claimed to have switched Russian samples for clean samples after testing.
Level playing field
The NYT admitted it could not verify the details of Rodchenkov's allegations while the Kremlin last week dismissed the claims as "defamation by a defector." CNN was not able to verify details of the NYT report.
Bach said an inquiry was already under way by WADA into the latest revelations but insisted that "we cannot take these type of allegations as given fact already."
Former Olympic fencer Bach, who won gold for Germany at the 1976 Games, refused to be drawn on whether he expected Russian competitors to be eligible to compete at the Rio Games in August.
"I will not speculate. We are waiting for the facts. Baswd on these facts we will take our decisions and we will take these decisions in a way to ensure a level playing field for all athletes around the globe.
"Sometime justice takes time and this we have to accept because the alternative would be to give up."
Outlining what he defined as zero tolerance, Bach added: "First of all everybody implicated could face up to a lifetime ban from the Olympics and this is not only athletes. This is everybody implicated."